Shazam is an app that's been on my iPhone since the beginning, and in fact, everyone should have it. Besides the fact that it's free, it's useful in a very innovative way: if you hear a song anywhere that you don't know the artist or name of, just pull up the app to hear it, and it'll tell you what you're listening to. I still use it occasionally to find new music that I hear and like out in the world, but I never really paid attention to updates -- they usually just got included in my monthly or so "download all updates" click. Apparently Shazam's been updating something fierce, however, and the newest version has all kinds of functionality that you might not expect.
At some point, they added in Twitter integration, so if there's a tune you want to share that way, you can do so. There's always been a way to share them via email, too, and they've spruced that up a bit by calling it a "postcard" (conveniently also giving your friends a chance to buy the music you hear, and probably put some change in Shazam Entertainment Ltd.'s pocket -- it is a free app, after all). But the most interesting new feature is that Shazam now tracks your location when you "tag" a tune, so that eventually, you'll be able to look at a map of where you found all this new music you like.
Sure, it wasn't exactly a pressing feature, but it is cool to see your "musical journey," and have that information about not only what you tagged but where you tagged it. Shazam is an app that's probably on your iPhone already, but it's worth another look.