This iPhone app makes it easy to access the hugely popular Pandora Internet radio site. Once installed, open the app and create a Pandora account. (If you’ve already created an account on your desktop computer, you can log into it via your iPhone.) Then, simply tell Pandora your favorite song, recording artist, or composer. Pandora scans its database for similar music, based on a wide variety of attributes identified by the Music Genome Project (pandora.com/corporate/mgp). It uses this information to create a personalized “station” based on your favorite song.