So I know we spend a lot of time talking about Threadless, but there are other sites that deserve your t-shirt purchasing love.
For example, the one pictured is "Killovision," a reprint from Go Ape Shirts. I like it because it seems like what would happen if David Cronenberg had directed Pleasantville in a decidedly grindhouse style.
Then you've got a great shirt from Diesel Sweeties in which it was stated that Red Bull would give you wings...but never specifically what sort of wings. "The energy drinks of the night...what sweet insomnia they make..."
For you Douglas Adams fans out there, there is a t-shirt, in silver foil on black, for Disaster Area--the rock and roll equivalent of Galactus--taken from The Hitchhiker's Guide to the Galaxy. That's available from ThinkGeek.
And last but not least, there's a great couple of restaurants here in Atlanta called The Vortex. I don't get to eat there nearly as often as I'd like. Their burgers are absolutely badass. Their symbol is a ginormous skull and they incorporated that into this zombie tribute shirt, which proclaims: "When there's no more room in Hell, the dead will walk to The Vortex." Burgers and zombies, what a combo. We love these guys.