http://www.vbulletin.org/forum/forumdisplay.php?f=15 - Check out various available colored and styled skins. Scroll down to the bottom and you will see a white box on the left with "Smooth Blue" visible. I love the navigational tabs at the top of the Smooth Blue which is the default on this forum. Very modern and updated, stylish.
Click on the 'arrow down' and you will also find Dark Blue, Stylish Green, Plain Green, Purple, and finally v3B Grey Style (this one we currently have). On at least some forums, you can "set" your color on your User preferences so it is always want you want.
And here is another set of colors and two styles - Fixed and Liquid. Available in White, Gray, Classic and Retro color plans.
http://www.vbulletin.com/forum/?styleid=11
-Theresa