There's a song stuck in your head. The chorus—the part you can't forget—goes, "Woo-hoo! Woo-hoo!" But what's it called? This is where Midomi.com comes in. You sing into your computer's microphone. Using voice- and music-recognition technology, the site compares your woo-hooing with its database of user-contributed recordings and finds a match: "Song Number 2," by mid-'90s Brit-pop band Blur.
What if you're tone-deaf, or the type who always gets the words wrong? What if you're too shy to sing above a whisper, even to your computer? Midomi co-founder Keyvan Mohajer says not to worry. "As long as a human can tell what you're singing, so can Midomi." So you shut the door and start crooning: "Suddenly, someone is there at the turnstile, a girl with colitis goes by." Midomi isn't fooled; you're singing the Beatles' "Lucy in the Sky with Diamonds," and you mean a girl with kaleidoscope eyes. The site links to a version performed by Slav, a user in France. His sweet, heavily accented version is mesmerizing. And you're in luck: He's recorded 247 other songs.