Sheldon has some cool shirts, in particular the Astroblast shirt, I love that one. The comic book geekery isn't my cup of tea though, but there are quite a few video game appearances/references as well as some good board game representation in the show too
The inane theme song always irked me. All history of civilization and no cosmology. If you're talking about the BBT, an awful lot occurred before 'the Earth began to cool'.