I saw a demo about a year ago, probably linked to from a blog somewhere, of a color picker. It wasn't the usual design nightmare color picker - it was a simple site where you gave it a color, clicked "generate", and it would randomly pick several other harmonious colors and show you what a site with that theme would look like.
I need that tool now. Do you know what I'm talking about? I've tried searching Google but am overwhelmed with crap and I can't find it on Memepool or Metafilter.
Update: Many thanks to Chris Pirillo for emailing me what I was looking for within 45 minutes. The site is ColorMatch 5k, as seen on Chris' LockerGnome. Unfortunately ColorMatch 5k is down right now, but ColorMatch 10k does just as well (in twice the space :-). Or this Flash version. Todd recommends Color Harmonies.