Thanks to high-speed connections and low expectations, this scenario has played itself out over and over again lo these past 10 years. Here are but a few examples of the decade's Next Temporarily Big Things, each one pushed out of its tiny, insular spotlight by something a little lower on the list.
Hype Cycle: 1998–2003
Key Artists: The Definitive Jux roster, Atmosphere, Blackalicious
What It Was: Underground rappers used frenetic noise, polysyllabic wordplay, and punk-inspired touring cycles to make a living independent of the perpetually fucked major-label machinery. Every rap fan was expected to only listen to either this or mainstream Hot 97 stuff—and be a total dick about it either way.
Creative Peak: Cannibal Ox, The Cold Vein 
Typically Effusive Praise at the Time: "You know the album will affect what you hear for years to come, and you can only guess at the ways its influence will be incorporated . . . [a] couple of 'street peasants' who managed not only to advance themselves, but advance music in the process. . . ." —Stylus magazine on Cannibal Ox, 2001
What Happened?: Rappers realized that "underground" was mostly synonymous with "broke." After blogs became more popular, the same rock writers that helped indie rap's ascent ignored it entirely from 2004 to 2008 in favor of in-depth, up-to-the-minute coverage of every one of Cam'ron's and Lil Wayne's studio farts.
Hype Cycle: 2000–2002
Key Artists: Kid606, Prefuse 73, Kit Clayton
What It Was: A diverse electronic-music mutation made up of prickly snippets and sputters, embracing the sound of malfunctioning gear, skipping CDs, and farting software. Also, Tortoise and Björk said it makes you smart and cool and handsome.
Creative Peak: The Clicks & Cuts 2 compilation 
Typically Effusive Praise at the Time: "Surely, we must afford Curry the same laurels we've bestowed upon Matthew Herbert and Björk." —Pitchfork on Safety Scissors, 2001
What Happened?: It furcated into inscrutable sub-sub-subgenres like "clickhop" and "blip hop" so rapidly that semantics (and Kid606's song titles) overshadowed the music. Also, after the Postal Service broke, everyone just admitted they want their electronic music filtered through watered-down indie rock if at all possible.
THE RETURN OF THE ROCK
Hype Cycle: 2001–2002
Key Artists: The Strokes, the Hives, the Vines
What It Was: Classic-sounding (read: boring) bands of nice people playing guitars (White Stripes) or cool people playing guitars (the Strokes) or fat foreign people playing guitars (the Hives) or pretty much anything that wasn't Britney Spears or Alien Ant Farm.
Creative Peak: The White Stripes, White Blood Cells 
Typically Effusive Praise at the Time: "The Strokes' music may be aggressive and grainy, but it's not nihilistic like rap metal; as such, it seemed like constructive accompaniment to the ongoing television footage of fires, body bags, twisted metal, and mangled landscapes." —Entertainment Weekly, September 24, 2001
What Happened?: The dying gasp of major-label clout, this was the very last modern-rock movement primarily propelled by the Big Bad Music Industry—and it barely took two years for them to fuck it up and start bombarding us with the Darkness and Jet.
Hype Cycle: 2001–2003
Key Artists: Peaches, Miss Kittin & the Hacker, Felix Da Housecat
What It Was: Somehow finding the common ground between Fashion Week and college radio, electroclash artists used tinny keyboard blips and hackneyed new wave clichés to help publicize their oversize personalities (and occasionally their music).
Creative Peak: None.
Typically Effusive Praise at the Time: "#1 still sounds fresh, with that same lightning-in-a-bottle feeling that Prodigy's The Fat of the Land had nearly six years ago . . . unlike all the empty pop music you hear on mainstream radio today, this is one pop album that gets it right for once." —PopMatters on Fischerspooner, 2003
What Happened?: Electroclash never really died—it just keeps renaming itself every three years. See the "electropunk" of MU, the "electropop" of the Knife, or the "wonky pop" of La Roux.
Hype Cycle: 2001–2004
Key Artists: 2 Many DJs, Freelance Hellraiser
What It Was: Putting two songs together cleverly—something that legitimate DJs have been doing since the dawn of time—suddenly became an OMG-worthy critical sensation once Freelance Hellraiser's Xtina/Strokes mash-up "A Stroke Of Genie-us" became the Napster-era version of Keyboard Cat.
Creative Peak: Danger Mouse, The Grey Album 
Typically Effusive Praise at the Time: "More than a century ago, the French writer Comte de Lautréamont praised the surpassing beauty of 'the chance encounter, on a dissecting table, of a sewing machine and an umbrella.' This year, similar encounters took place on laptops across the country."—The New York Times, 2002
What Happened?: Jay-Z and Linkin Park teamed up for the groan-worthy 2004 "mash-up" project Collision Course and ended any chance of this being cool ever again. Girl Talk emerged in 2006 with a sound so sophisticated that it made your roommate's hilarious "Fugazi Osbourne" project look even stupider than it was.
Hype Cycle: 2002–2005
Key Artists: The Rapture, Radio 4, !!!
What It Was: A mix of early-'80s dance-y post-punk bands like A Certain Ratio . . . and early-'00s posturing about how you own an A Certain Ratio record.
Creative Peak: The Rapture, "House of Jealous Lovers" 12-inch 
Typically Effusive Praise at the Time: "Bands like the Rapture have sent their message: The rock show was not meant to be a collegiate study. We have all stopped caring what snotty academics find acceptable, because now there is real, true, palpable fun, and it is the greatest liberation." —Pitchfork, 2003
What Happened?: Franz Ferdinand figured out how to get real money, so dance-punk's coolness sputtered to a halt once it spawned watered-down major-label cash-ins (the Bravery), watered-down indie-label cash-ins (Bloc Party), and super-glossy pop cash-ins that still defy all logic (Ashlee Simpson's 2005 single "Boyfriend").
Hype Cycle: 2003–2006
Key Artists: Dizzee Rascal, Wiley, Kano
What It Was: Inner-city London kids spawn a mean-mugging, minimal mix of U.K. garage, American hip-hop, Jamaican dancehall, and, apparently, PlayStations eating themselves.
Creative Peak: Dizzee Rascal, Boy in Da Corner 
Typically Effusive Praise at the Time: "Pressing play on the East Londoner's debut was akin to hearing Public Enemy for the first time—all alien sounds and harsh DIY bleeps, plus of course Dylan Mills' brilliantly edge-of-chaos rhymes. MC culture, he showed, could deliver more than pop garage or pallid Americanisms."—The Guardian on Dizzee Rascal, 2003
What Happened?: The indie snobs who stumped for it suddenly realized there's actual American rappers with shitty backgrounds to fetishize (see "trap-rap"). Lady Sovereign got signed to Def Jam and wasted some of Jay-Z's money. Dizzee Rascal started hanging with Calvin Harris, folding grime into a Brit version of the same boring electro coke party that Flo Rida hosts every weekend.
Hype Cycle: 2004–2006
Key Artists: Devendra Banhart, Joanna Newsom, CocoRosie
What It Was: Dudes with beards and ladies in flowing dresses playing weird and/or pastoral strum. Pretending you were an animal or child apparently helped.
Creative Peak: Joanna Newsom, The Milk-Eyed Mender 
Typically Effusive Praise at the Time: "This music makes my heart feel stout, and enables me, with my eyes, to breathe fire." —Dave Eggers on Joanna Newsom, Spin, 2004
What Happened?: After curating the scene-defining Golden Apples of the Sun comp, Banhart got all pissy about being lumped in with a scene. He tried to change its name to "naturalismo," but then realized it's probably more fun just to lay low, make records, and occasionally make out with the Queen of Naboo.
Hype Cycle: 2004–2007
Key Artists: Boris, Wolfmother, Dead Meadow
What It Was: Dave Grohl's unexceptional Probot vanity project brought attention to avant-metal label Southern Lord, making it cool for the ironic-ringer-T-shirt set to share warm PeeBeRs with the denim-jacket-back-patch set. Soon, bands like the Sword, Priestess, and Saviours brought all the energy and aggression of metal without zitty geekazoid tropes like "chops."
Creative Peak: Mastodon, Leviathan 
Typically Effusive Praise at the Time: "If Sunn 0))) is the ZZ Top of experimental metal, with matching beards and Gibson Les Paul guitars, Boris might be the Kraftwerk, or the Ramones, or even the Jimi Hendrix Experience, depending on the album." —The New York Times Magazine, 2006
What Happened?: For most people, standing through two hours of Sunn O)))'s fog machine and drone turned out to be "not really my thing." Indie rockers started their own terrible metal bands (David Pajo's Dead Child, Rob Crow's Goblin Cock), and the burnouts nerds laughed at in high school resumed shaking their heads at us all.
Hype Cycle: 2005–2006
Key Artists: E-40, Keak Da Sneak, Mistah F.A.B.
What It Was: Delirious, sproinging Bay Area rap music known for its minimalist bounce, odes to going crazy-cuckoo-bonkers, and vast dictionary of slang—including the ever-popular YouTube blooper staple "ghost-riding the whip."
Creative Peak: The Hyphy Hitz compilation 
Typically Effusive Praise at the Time: "It's by far the best party going on in hip-hop right now. . . . It's hard not to hope that the Bay Area's turn is next, that we're just one breakthrough hit away from a hyphy takeover." —Slate, 2007
What Happened?: A 2007 Mercury News piece detailed an array of poor business decisions—everything from signing bad contracts to rappers just straight-up missing meetings—that left hyphy standing alone in its stunna shades.
Hype Cycle: 2006–2008
Key Artists: Justice, Simian Mobile Disco, Boys Noize
What It Was: A term allegedly coined on the Hollertronix message board, "blog house" described the nu-electro sounds, mainly from French labels like Ed Banger and Kitsuné, of electronic bands that sounded like rock bands—a/k/a stuff an earnest 19-year-old blogger wouldn't recognize as the Hackers soundtrack with a Fader co-sign.
Creative Peak: Justice, † 
Typically Effusive Praise at the Time: "A creative tour de force, Justice have unleashed an era-defining album for the children of acid house. Never mind Daft Punk, here's disco punk." —The Guardian, 2007
What Happened?: For fuck's sake, we called it "blog house." It was the fickle attitudes of dance music fans combined with the even fickler attitudes of Internet users. It's shocking it lasted as long as it did.
Hype Cycle: 2007–2008
Key Artists: Times New Viking, No Age, Psychedelic Horseshit
What It Was: The same crappily recorded garage-punk tantrums that have been around since the days of Count Five—but now on trendy indie-rock record labels you've heard of!
Creative Peak: Jay Reatard, Matador Singles '08 
Typically Effusive Praise at the Time: "No wonder they don't care about certain standards of recording quality: They are their own Alan Lomax, immediately 'getting down' the wild, the weird, and the strangely alluring on a single-microphone tape recorder." —Prefix on Times New Viking, 2008
What Happened?: In this accelerated age, a months-too-late MTV News trend piece effectively kills cool dead.
Hype Cycle: 2009
Key Artists: Memory Tapes, Washed Out, Neon Indian
What It Is: An Internet fanbase starving for a sequel to Animal Collective's Merriweather Post Pavilion satiate their appetites via bands with less bread-'n'-butter hustle, but plenty of mushy textures, summery melodies, tape distortion, and names like Ducktails and Reading Rainbow that drive home the fact that, yes, we were kids once . . . remember?!
Creative Peak: Toro Y Moi, "Blessa" seven-inch 
Typically Effusive Praise at the Time: "Remember tape cassettes? No, me neither. Not until Alan Palomo's Neon Indian reminded me how it sounded when a tape played so much it unraveled in the deck." —Pitchfork, 2009
What Happened?: Not technically dead yet, but 90 percent of writing about glo-fi mentions "the summer" in some fashion. And summer's been over for, like, four months now.
'00s MICROTREND GRAVEYARD
Ghettotech, microhouse, folktronica, New Weird America, schaffel, crunk, trap-rap, post-metal, screw, baile, Baltimore club, snap, nu-balearic, moan-wave, grindie, deathcore, nu-rave, juke, wonky, skweee, dubstep, kuduro, jerk, hypnagogic pop, crabcore.