When my raver ex-girlfriend moved away several years ago she started sending me letters telling me about house tracks she liked. Sometimes she didn't know the names of them, so she'd invent titles like "The Snail Song" or "The Beep Song." If you've spent enough time in decent dance clubs in the past five years you probably have your own anonymous favorites--something you call "The String Section Song" or "The One That Needs a Rakim Verse"--and there's a good chance the people responsible for them are Morgan Geist and Darshan Jesrani, otherwise known as Metro Area. There was a moment a few years ago, right after they released their debut, Metro Area 4, and Geist turned up as a remixer on the Rapture's "House of Jealous Lovers" single, when dance music mavens predicted the duo would move electro off the dance floor and into the living room. But they've steadily avoided the fame they probably deserve, instead dropping a string of low-profile, sequentially numbered, increasingly nuts 12-inches that crossfuck just about every good idea from the last 30 years of dance music and even a few--like disco strings--that border on irredeemable. Maybe you've never heard of them, but luckily your DJ has. M50 opens. Fri 8/25, 10 PM, Smart Bar, 3730 N. Clark, 773-549-4140 or 312-559-1212, $10.