Just saw this post and hmm'd about it a bit. We could fire up a post on Imgur to advertise the server. There's quite a bit of interest in D&D on there, though mostly PnP.
Not sure what the best way to do it would be though. Ridiculous PnP stories (or how I wrestled a dragon to death mid-flight with a natural 20) have done well. I'm not sure that blatent advertisment would necessarily get far, but perhaps sharing some cool stories with suitable screenshots or pictures might. Like if I did one, I'd probably do one about Raghat and say how I went from getting the shit kicked out of me in an alley to illegal cage fighting and then leading an orc army, before being defeated spectacularly.
Gromfia, Thayan shenhanighans, no end of Eclestian Order controversy.
Not sure entirely how it works but I think once a post gets more than so many points (7? 30?) it goes to the "front-page". There's also reddit which is quite similar, though I'm less familiar with it and I think it's better suited to discussion than image sharing. Stick a few of Thune's MFW in there and I think it could do well.