This isn't much of a heads-up, but I invite anyone to come join the 100 day surfaces and materials challenge! This is going to take place on Conceptart.org (link to sign-up thread here) and its going to be a lot of fun.
If you're not sure what surfaces and materials means, well, it can pretty much mean anything! Here are a few awesome deviations that may help explain.
Making spheres isn't the point of the challenge, just the act of practicing painting different materials/surfaces/textures is what matters. Join us!