Sure, its name is a bad pun, but Adobe Kuler is none the less very useful. It’s basically an overblown colour picker. If you’ve ever worked with Photoshop or something similar you’ll be right at home.
I told you about the problems I had painting my Sol Invictus marines last week. I need something to accent the drab gray. Since gray is neutral, I instead started with the turqouise I intend to use for their eyes and power weapons. Lo and behold. In the picture above you’ll see that the complementary colour is a heavily saturated rusty brown. Good times, now I have something to work with!
Apart from giving you a scheme with complementaries, Kuler can also do triads (and some other things). The triad above is pretty boring, but it’s nice to know that I could use gold and purple as an accent if I’d like to. For characters, perhaps?
Of course, there’s also the “create from image” function. Fun to play with! Remember that if you create an Adobe account, you can save your themes on their server.
To learn more about colour theory, here are a few links to start you off:
Tigercolor has an introduction. Read this. I mean it – do it now.
Sandwyrm at The Back 40k wrote two excellent articles: Part 1 and part 2.