I think this was suggested a few times before, but I don't believe a conclusion was ever drawn to it(?) Anyway, the suggestion is simple. Allow users to upload a cover that will be displayed at the top of their profile. There's not particularly any benefit to it, other than it looking nice, I guess. I suppose you could say it's just a cosmetic feature. Also, I think it would be obvious how inappropriate covers are dealt with — the same way that inappropriate usernames, profile pictures and signatures are.