At the incline leading to the shuttle at 42nd Street/Grand Central Station, a tumbling dwarf in a rhinestone shirt is folding an exercise mat. An hour later, at the Union Square terminal, Michael Jackson refuses to perform until the bemused crowd scuttles closer to experience his broke-ass "Billie Jean." A distant saxophone overheard at Penn Station leads to a dead end, and while waiting for the A to depart at 23rd, you spot a guy playing "Rock Around the Clock" on steel drum; seconds later, he and his song disappear. At 59th and Lexington, a young man with baby dreads uses four buckets and two sticks to channel William Hooker; a few stops away at 42nd, three dreadlocked drummers, one bongo each, establish a slower tempo, seemingly patterning their rhythms on the guy at 59th. If you go quickly between two stops, a call-and-response develops.

Missed opportunities, half-seen sets, and chance encounters make subway performance one of the more dynamic musical scenes in New York City. A few musicians, though, emerge as fully developed characters after a passing glance: the metal-head duo at Times Square who wailed endlessly on "Hot for Teacher," the Solid Gold J-train dancers, four Hispanic men in sombreros pummeling flamenco guitars on the M. Though many of these performers are classically trained, the most interesting are those who integrate their underground surroundings into their aesthetic, twisting the subway's screech into an aspect of the project.

One such performer, Ron Raffel, turns even James Taylor-style soft rock into a shambling take on John Fahey's psyched-out Americana. Serenading passing women and engaging children in conversations mid-song ("Thank your mom for the money"), he lets his long hair fly, his head shakes, he crouches and stomps his feet. Once in a while he pulls a wobbly Chuck Berry duckwalk before shifting back into his signature posture. Even as he tunes, he lets out an "ouch" and recoils during particularly sharp or flat notes. Often sporting a contrasting black beret and white sneakers, Raffel, 51, has steel blue eyes and a scruffy gray beard, and can be spotted at the downtown and uptown F at 14th Street/Sixth Avenue station. He turns standards like "Imagine" into his own composition through reworking certain passages and endlessly repeating others. Recently, in the midst of a 15-minute version of Neil Young's "Old Man," Raffel drawled each word in his smoky caterwaul, holding on to the last syllable while a train stopped, paused, and continued on its way.

More purist than trailblazer, Zack Heru covers British Invasion tunes, as well as a couple by Buddy Holly, with eerie vocal felicity: Lennon sounds like Lennon, "All My Loving" is Sir Paul, and he seamlessly switches between the two in "I Want to Hold Your Hand." Smiling constantly and ecstatically while strumming an acoustic guitar, the dashiki-clad, 46-year-old African American White Plains resident has shaved clean one side of his head and has managed to make eye contact with almost every passerby in the busy 1/9 tunnel at 14th Street for the past four years.

Moving beyond the guitar, Natalia Paruz of Queens claims expertise in the musical saw, theremin, four-in-hand bells, toy piano, and 36 pitched Austrian cowbells. At 28, Paruz has been playing saw in the subway for about 10 years. Though she's been on Broadway and at Town Hall, collaborating with Garrison Keillor on NPR's Prairie Home Companion, she continues to haunt the 6 at Astor Place, 53rd, and 28th, and the N/R at 59th and Lexington. Unfortunately, three years ago—after receiving a $150 fine in Times Square—Paruz was forced to file the teeth off her 32-inch three-and-a-half octave French saw when the NYPD saw the instrument as a potential weapon. Luckily, her 15 other saws remain intact. Paruz, who is also able to tap-dance while tickling the ivories, can be found on the Web at sawlady.com.

Harlem's William Ruiz, 34, also on the Web (williamruiz. net), is a thin man with a long ponytail, chiseled face, and intense concentration, who often locks into a rhythm until he seems ready to pass out. His instrument is a traditional Taino drum made from a hollowed-out log. Performing in the subways since December 2000, Ruiz's work consists of solo improvisations based on his own compositions as well as collaborations with other percussionists using various traditional rhythms: Native American, Middle Eastern, jazz, big band, blues, Latin American, East Indian. He also leads a sextet, the William Ruiz Ensemble, in which he combines professional stage artists with street musicians. More ubiquitous than many subway performers, Ruiz moves between 34th Street and Seventh Avenue on the 2/3, 4/5/6, and L at Union Square, E at 53rd and Lexington, the uptown A at Times Square, 4/5/6 at Grand Central, and the 6 at Hunter College.

Perhaps my favorite performer, though, is the old man who plays an off-kilter harmonica amid the literary frescoes lining the tunnel between Fifth and Sixth avenues at the 42nd Street station. Rolling his pants high and often involved in time-consuming pre-set preparations, he blows one note on the harmonica—cheeks extended—and the sound remains opaque, so you can never figure out what he's going for. His weirdly affecting minimalism contributes a hushed high-end to the subway's massively scattered and oddly pitched orchestra.