As I'm a part of various different forums, each one has the ability for each member to have more than one userbar or 'forum rank' so to speak.
Here is an example of one of my own:
What I'm suggesting is that say if a member is a moderator and a donator, then they would be able or eligible to have the donator and moderator rank on their forum account, or if someone was an ironman and donator they would be able to have both ranks and so forth. I'm not sure what type of implementation it would require, but it would make the forums look more intricate and nice.