The design team here at Viget Labs has been using Adobe Labs' kuler
since shortly after its release as a technology preview/beta in 2006, and we frequently reference it for color inspiration. Two features that distinguish it from other color tools are: 1.) It's web-hosted and available through a free stand-alone app or Adobe's CS3 software.
According to the Adobe Labs Web site, "kuler is the first web-hosted application from Adobe Labs designed both to stand alone and to complement Adobe® Creative Suite® software
. Built using Adobe® Flash® and ActionScript 3.0, kuler is all about color: color for exploration, inspiration, experimentation, and sharing." 2.) The kuler community.
Having a great tool doesn't guarantee you'll create that perfect combo with it. It's satisfying and extremely useful to see what other users are creating, plug in to what's most popular, and save your own custom library of color combinations. Designers and non-designers alike will find kuler
to be helpful, inspiring, and engaging. If you haven't already, be sure to check it out