TuneWiki for Google Android
The free music application for Google Android not only plays your media, but it also helps build your library with songs and YouTube music videos. An additional search for streaming lyrics attempts to get you singing the right words at the right time.
TuneWiki doesn't ace everything it sets out to do, but if you're willing to give it some leeway, you won't be disappointed. Check out the First Look video here for more details and an up-close view of TuneWiki in action.