Ok, so, this is the thread where you put the URL's to any cool resources for art and design, whether it's stuff you gotta buy, freeware to download or web applications one might find useful.
I'll kick things off with this free colour scheme designer web app:
http://colorschemedesigner.com/
and Adobe's Kuler, another colour scheme designer that has many more advanced features.
http://kuler.adobe.com/