Shazam is one of those essential mobile apps, and it’s on the Windows Phone 7 marketplace right now for free. It works exactly like the same app on other platforms: if a song is playing in the background, Shazam will “listen” and try to name the song. Most of the time, it’s right. Better yet, Shazam will link you to the song in the Zune marketplace so that you can download it (if you have a Zune Pass) or buy it.