Recently, ColoRotate has been released. ColoRotate uses a 3 dimensional approach to picking colors wich it claims is closer to the natural way the brain processes colors. It relies less on the sliders that are common in kuler and other tools. Color schemes you create can be shared in an online community, similar to kuler.
I have played around with the tool a little bit and like it, but it requires a bit of studying and practice before you get the hang of playing with the 3D axes and their impact. This tool is likely to appeal most to graphical professionals.
Having said that, the web site contains a good introduction article to the art and science behind picking beautiful color schemes.