Found this great article called “5 Web Design and Development Tools I Simply Can’t Live Without (and Why).”
Our favorite is Kuler. Check out the author’s description below. (but you should still take a look at the other four)
Color is the unsung hero of web design. Seriously, a good color palette can draw your audience into your site and give them a powerful feeling of immersion, and (best of all) keep them coming back to your site (which is one of the points of good design, isn’t it?). When it comes to tools to help you not only build color palettes based on color schemes, but also translate colors into usable hexadecimal codes, there is nothing better than Kuler. While there are other solutions out there (ColorSchemer Studio comes to mind—which is both Mac and PC), I simply love Kuler. It is hands down my one stop shopping spot for all of my color palette developing needs. One of the cool things about Kuler is that its not only a tool for building your own color palettes (and getting the hexadecimal values of those palettes), but it has social features that let users browse and rate other people’s palettes. The other great thing about Kuler is that is completely online and completely free. The only real “cost” is that you will need an Adobe ID (which is free) in order to take advantage of Kuler’s more advanced features (especially the social stuff).