I use a variety of color picker sites for inspiration, but I most frequently use Adobe’s Kuler (pronounced ‘cooler’). Like others, it has a variety of displays from which you can pick and adjust colors, a social aspect providing a means to benefit from the more artistic eyes of others, and the ability to export a set of swatches. I especially like the recently added ability to upload photos and have Kuler extract colors from the photo. You can influence which colors get extracted, selecting a ‘mood:’ colorful, bright, muted, deep, or dark. Of course, you can adjust which colors are picked as you wish. Watch a screencast of using the kuler image uploader/extracter.
Last week at the Adobe Summit, I encouraged the Kuler team include a tool for testing out color combinations for accessible contrast in brightness and hue so we don’t have to go back and forth between kuler and a validator, adjusting and copy/pasting values until we have a usable combination.
Kuler’s API is available and there have been some interesting results. There are a few blogs dynamically changing background colors using kuler themes. There are panel extensions available for Dreamweaver, Fireworks, and Flash. The Adobe Labs Kuler page has links to these and others. Have fun!