I am so bummed! Scrap Matters is closing so there goes KimB's color challenge! It's one of my faves and I will surely miss it. I will follow Kim to whatever store she moves to and hope that she can do a color challenge there!
In the mean time, I have discovered PixelScrapper which has a designer challenge as well as a blog train every other month. Check them out - there's lots of other stuff going on also.