I wanted some shirts that showed my disdain for cancer. I found Cafepress, which has quite a few shirts that align with my sense of humor.
I couldn't find a dark shirt (I sweat a fair amount more now that I'm on Gleevec) that had the right saying. So I made some.
Cafepress is actually a pretty cool service. You can upload any picture you want and put it on a variety of clothing.