In the land of music identifying apps, we fall into the SoundHound camp (versus Shazam). Yes, we know Bing can ID music and it is pretty good, but SoundHound right now has the better library for IDing songs, making it more accurate for us--plus we dig that one-button tagging option.
While version 1.0 was pretty solid for a first-release, it did have at least one major issue: the Facebook posting did not work for many. That's now fixed in v1.1 which just hit the Marketplace. In addition, v1.1 brings "faster search results" and "artist social channels" which allows to easily follow musicians on social networks...or something. Also, the quick Tile graphics have been updated wit a more identifiable look.
Pick it up for free here in the Marketplace.