Remember Lyrical, the free app that lets you look up lyrics for the currently playing song? TuneWiki does it one better, spooling out lyrics as the song plays. (All that's missing is the bouncing ball.)
With TuneWiki for iPhone (and iPod Touch), you choose a song from your library (using the TuneWiki interface, not the standard iPod menus), then watch the lyrics scroll past as it plays.
That's assuming, of course, the song has already been "time-synced" by another user. If not, you'll have the option of advancing the lyrics yourself so the app will know the sync points in the future.
TuneWiki also lets you stream music from countless Shoutcast radio stations, and works the same lyric-subtitling magic with most songs.
The app includes a YouTube video search option and supports both Twitter and Facebook: it can automatically update your status to show what song you're playing. It even emulates the TuneWiki site's mapping option to show you who's listening to what in various parts of the world--including yours.
In other words, it's a pretty cool app--or would be, if not for the generally atrocious interface. Browsing your song library is a slow, awkward process, in part because TuneWiki lacks the alphabet-shortcut menu on the right edge of the screen.
Meanwhile, menu options and icons aren't logically designed or organized. Most buttons don't look like buttons; it's too easy to get bounced out of the app by, say, the YouTube or download buttons because you didn't know their functions.
On the other hand, once you learn your way around, it's pretty cool--especially if you like to read lyrics while you're listening to music. The subtitling works pretty well, and it's hard to complain too much about an app that costs nothing to use.