ColourLovers is a combination community blog and social tool, with a whole bunch of cool colour palettes and other tools available. I'd love to become a member but I wonder if I'd have the time to really check everything out!
In one of the posts on Multi-blends, I found this tool to create colour blends which I thought was pretty great as well.
Its definitely a great site... perhaps better than Adobe's Kuler... but just not as cool :)
[edited for spelling...added: interesting note, ColourLovers is the first site in a google search for 'colour palettes'... if you spell it right. GO SEO!]