I just submitted my first-ever entry to Threadless.com because of their recent contest to design a t-shirt inspired by Marvel's Iron Man. I simply couldn't resist trying my hand at it. I mean, who doesn't think Iron Man is one cool cat? Since idea is key, the hubby and I brainstormed over ideas and I thought his idea was great so I set about making rough thumbnails stick-man style (not Gangnam style :D) before fleshing out the final design and characters. As he followed the comics growing up, I followed his guidance to use the old-school Iron Man. I myself tended to favour the X-Men, X-Factor and Thor titles in my brother's comic collection. One of the stipulations of the contest was that it should be inspired by the comic not the movies so fortunately our idea wasn't inhibited by that.
If you have time, please feel free to check out the contest page and vote. There are some pretty amazing designs on there.