A more streamlined mailbox that's more mobile-friendly. For examples, when viewing my messages, I have to rotate my phone to landscape orientation to have everything appear properly. It's a small tweak, but it would make messaging easier.
Some new profile features? Not to make it look like a dating site by any means, but maybe the option to add more than a tiny profile photo (or multiple photos), and a short Q&A section related to the person's experience with naturism. I often find myself reading through a post, and I'll see someone's post (or reply), but then I'll find myself trying to remember "was this person raised a nudist from birth, or how did they get into it"? And the only way to figure that out is to dig through their post history, or look to see if they have an AMA topic somewhere.
Granted, many users would probably not fill it out even if it was there, but just an idea to get the ball rolling.