A freelance web designer named Dicky has put together a handy list of online color tools for web designers. The following link is for anyone who has ever found themselves in dire need of a "color wheel, color scheme, color palette, color picker, and etc."
The one thing Dicky seems to ask in return is that if you like it, you Digg it.
Here's the list:
The Ultimate List Of Online Color Tools For Web Developers