I think the OP is referring to the game itself, I can't see "Rankings" as being a forum suggestion.
We have the ability to set ranks based on posts, but most people go in and out of clan ranks and we'll probably have special usergroups setup for different things as well as custom titles for some competition winners.
I know you can get achievements on a forum (like GH), but I don't see how that'd attract people to their servers (or their forums particularly).
I also don't particularly like the idea of achievements and rankings in-game either, mainly because the best players (who don't play much) probably won't appear.