i was looking at some of the 'all hail megatron' comic cover art and some of that or art along the same style, i think would look quite good on a shirt.
alot of people will wear the autobot/decepticon faction symbols but not much else that is available. perhaps we need art that is more suited to the age group of the collecters [20's and 30's correct me if im wrong] and no so much the stuff for smaller children
just a thought