GameStop (NYSE: GME) recently announced that it would start selling comic books in about 40 of its namesake and ThinkGeek stores in a test program. That represents a mere sliver of the video game retailer's 7,216 stores, but it could help the company diversify away from its core gaming market, which is being disrupted by digital downloads.In a statement, GameStop called the effort a "small launch" that would complement its growing collectibles business.