My dad wrote an app. It’s called Color Hints, and it’s a pretty nifty thing. It allows you to analyze the colors in a picture, and using that information find what colors will coordinate. You can take pictures or pull them in from your photo roll, but it also has a built in browser, so you can sample colors off web pages. That way, when you see a paint you really like, you can sample the color and save it. Not only will Color Hints help you find coordinating colors, but it will tell you all the values of the color you’ve sampled- and that means you can have matching paint mixed to order.
He wrote it for my mom, who’s been doing a lot of quilting recently. She uses it to log fabric swatches and know which go with which, but it’s just as useful in the hands of a designer (interior, industrial, fashion, take your pick…), and it’s a pretty decent tool for teaching color theory as well.
It’s in the app store now here, and I’d recommend it highly. I’ve been running the beta for a few months now, and when it comes to helping me pick what art to hang in the dining room to go with the carpet and table, there’s nothing else quite like it.