As one who has been both a moderator and an admin on other forums, I can tell you it isn't all that great.
People tend to give your opinion more weight (and therefore, you have a LOT more responsibility) than they would if you were just a regular person. YOu can't goof off as much or make as many inflammatory posts, unless the forum is of a nature that can support that sort of thing. You have to act more responsible. It's kind of a drag.
And then there are the constant, relentless petty complaints about the layout of the forum, some glitch or bug that someone has on their computer, or they forgot their password, or the search function doesn't work, or someone hates avatars and wants them done away with, or you disable avatars and someone gripes becaus ethey want them, etc. If anything isn't perfect, it doesn't have to be your fault- they'll gripe to you and want instant results!
If the server your forum is on goes down, they complain bitterly, even if there's nothing you can do about it but wait for the server to be fixed...or you return and they have left en masse for a "more reliable" site (yeah, right...). There is always ample criticism...
Worst of all, you have to make hard decisions, such as a friendly, outgoing, upbeat, very helpful member who now insists on a logn signature that is advertising their business or product, or the person who mentions their money making venture in an advertising way, in every other post, despite rules to the contrary and a seperate forum category specifically for sales and business. Or a member that you've always liked and gotten along with who suddenly flies off the handle and insults someone else and just loses it, starting a huge fight and uproar. Or the ever present mutiny in the wings, and the tendency for such forums to split and splinter off uselessly because of petty disagreements. Or the proselytizing relentlessly and obnoxiously when it doesn't relate to the topic at hand....
No, being a mod or admin isn't such a hot cup of tea if you want my opinion.....