Final Fantasy MODs

is there a website where people group together and create MODs and other conversions for some of the Final Fantasy titles?

Qhimm and its Forum is one such place. It focuses mainly on modding FF7 (a bit of FF8 and FF9) and it has quite a nice community.

They don't get super extensive, but romhacking.net offers a lot of patches for games that change a lot of how they work. Mostly re-translations and whatnot as far as the Final Fantasy games are concerned. But I have seen some people completely rework a couple of the games. I think our own black_orb has a hack for FF1 where you play as the shopkeepers rather than the warriors of light. But I'm not positive he has it hosted on that site. It's just a good place to start if you're looking for hacks of the older games