Play is an essential part of the learning process. Since I don't believe that's it's entirely appropriate to do that playing on my client's dollar, I do experiments on my own time to help me learn new things - From time to time, I'll post details about some of the larger ones.
Rendering I've spent a lot of hours of my own time figuring out the specifics of the Mental Ray renderer. Time permitting, I'll post a few more renderings here.
Matching a Sketch This was an experiment in following a sketch through to completion, and in matching perspective.