TuneWiki is an awesome app for the Android G1, I absolutely love it, its in the market and available for free. Some of the features I like are the auto album-art download and auto-lyric search capability, plus you can also quickly pull up a youtube video of the music your listing too!
TuneWiki is one of the top 10 winners of the Android challenge Phase II
Checkout a video:
Developers site here