Adobe recently updated their Kuler Web site, and have released a Kuler App for the iPhone. I've written about Kuler previously here. Kuler is "a cloud-based application for making color themes using an iPhone or your browser."
Most notably, the Kuler Web site uses standards-based responsive design, so it works beautifully on any browser on any device.
The Kuler app for iOS makes it super-simple to create color themes using the phone's camera. You don't even need to take a photo. Just point the camera at a scene that inspires you, and Kuler attempts to capture a color scheme from the scene.
Also, Kuler finally supports CMYK colors, in addition to RGB, HEX, LAB, and HSB!