River to River is the sort of secret weapon free summer arts series in NYC, with more appealing surroundings than the Williamsburg Waterfront and less pomp and circumstance than the line- and child-ridden Celebrate Brooklyn stuff at Prospect Park. Just roll up wherever, and watch for a while, basically. The festival will also put a smaller caliber of indie band on a big outdoor stage–everyone from Ted Leo to the Vivian Girls to Devin the Dude have played their South Street Seaport venue–and this year, the booking is typically on target: Bear in Heaven (July 9), Thee Oh Sees (July 16), Free Energy and Best Coast (July 23), Avi Buffalo (July 30), and YACHT (August 6), plus more to be announced soon. Bang on a Can, the 12-hour annual new music extravaganza, will return to the World Financial Center Winter Garden on June 27, and Antibalas will grace Castle Clinton on July 22. Look for a full 2010 schedule to be posted at rivertorivernyc.com come April 19. It’s almost summer already, huh.