This is one of those simple but very clever ideas that makes you exhale softly, while sighing "I wish I'd thought of that".
It's Last.fm + YouTube = music goodness.
Enter your last.fm username, or the username of someone whose music taste you trust, and it plays music videos from YouTube of all those artists. If you're not Last.fm'd up, just enter an artist, though that doesn't have quite the 'wow' factor.
Any other pet mash-ups you'd care to share?
