Mathiole is the flickr code name of Matheus Lopez, a brilliant Brazilian graphic designer, who's been doing some absolutily cool t-shirt designs for a few sites, such as Camiseteria and my favorite, Threadless.
In his flicker stream there's plenty of his work. There's all kinds of themes, from political satire to soccer. I don't need to tell you how much this guy is talented, just take a good look at his designs and enjoy! Cheers! ;)