GirlfriendShowoff.com is a place for boys (and girls I guess) to show off the women in their lives. It is not intended to be a porn site, but it will more than likely have some of that. It turns out that guys like pictures of their girlfriends/wives naked. Who knew?
Anyway, the purpose and capabilities of the site are rather obvious. Show off what you got. Comment on how lucky (or unlucky) other guys are. Most of all, be nice... this site is meant to be a community and douche bags ruin good communities.
About Robert, the founder? He's just a Vermonter / web programmer currently located in Cambridge, MA that noticed on every car/computer/anything forum on the internet there is always a 'post a picture of your girlfriend' thread. On most of those forums, you can't post naked pictures but the thread always becomes a good one. So, why not make a site under the same idea right? Is his girlfriend on this site? Absolutely. Is yours? Hopefully!