The Shazam app for the iPhone doesn't kid around. The first thing it does when it loads up, after giving you a little run down about how it works, is listens for what music is playing in the background. This may catch you off guard at first, considering that those new to the app might not have had their iPhone placed correctly to let it listen to the song in question. Once you've gotten over the confusion, Shazam is a music recognition app for the iPhone.
Shazam will try and recognize whatever music is playing when you press the Tag Now button. Once it identifies the song, it allows you to do quite a few things. First, you have the ability to preview and buy the song in the iTunes store. Now, if you're not connected to WiFi when you press the button, the iTunes app won't do anything for you. You can also view the video for that song in the YouTube app.
If you're more into personalizing the tag you've just made, you can attach a photo that you've just taken or one in your album to it. Plus, you can share the tag through email or delete it from your saved tags. The information for the album the song is off of does pop up as well, providing you the artist name, album title, genre, label, song title, and even the album art.
Shazam does a pretty good job of recognizing the song you're playing, if it's loud enough of course. As it relies on a database somewhere not on your phone to recognize the song, the sending period can take awhile. Overall it's a great app, but it doesn't really look that pretty and doesn't offer that much over the other music recognition apps.