Adobe has this tool (maybe they will build it into Photoshop Version.Next!) at Kuler.adobe.com.
With it you can take any picture and turn it into 5 color themes -- mathematically balanced to work together.
For example this image:
Goes to this:
I'm in design love.
Of course, like all early infatuation, my lust is tempered by frustration as I get to know Kuler. For example, Kuler is built into Adobe CS4 -- but not the photo tool, so I will be at the mercy of Adobe never taking it down if I want to love it forever and ever and ever. Also, Kuler, like the punk rocker you dated in college, isn't ready to be brought home to Mom. Specifically, there's no way to get Adobe Swatch Files into Dreamweaver -- I'm going to have to ink dropper each color to get its hex code if I use the ASE files. (And really, Adobe, "Macromedia didn't support ASE files when we bought them" doesn't cut it as a reason to not allow Dreamweaver to pull hex codes from an ASE file. That was four years ago! Get over it!)