Since I work with the onilne ressence for my company and know nothing about it, I find myslef working with graphics and such as well.
I found these sites and they provide a lot of info about colors and which ones go together.
Some are web2.0 graphics as well.
http://garmahis.com/reviews/color-matching-color-schemes-and-palette-design-with-6-online-tools/
http://aviary.com/tools/phoenix
http://www.nofunc.com/DHTML_Color_Sphere/
http://www.wellstyled.com/tools/colorscheme2/index-en.html
http://kuler.adobe.com/#themes/rating?time=30