If you don't want to go full blown into the adult thing, but still want something that will attract some attention, then check out T-Shirt Hell. Their product is raunchy enough to get people to click, but not so hardcore that you'll get a shitload of hatemail.
http://www.tshirthell.com/cgi-bin/af...gi?id=evildick
They sell funny and offensive t-shirts that are always topical. You make $4 per shirt, which is alot better than Amazon commissions. And I doubt you'll find a "I fucked Osama's Mama" t-shirt on Amazon.