diy expert was a class used to access a private forum that was later deleted. but the memebergroup stayed.
guest is for those who do not have an account. (i thought we had guest posting disabled but i don't remember)
newbie-Junior Member-Full Member-Senior Member-God Member are based on post count and do not (currently) have any asociated privilages.
Trade gets you access to the trade forums
AE3 Admin was created for fwl-enginner when we were planning to copperate with his AE3 (which doesn't seem to be going anywhere fast right now) and has the same privilages as trade.
Member was created for the member only forums which were later abandoned.
ATT Moderator is for moderators who have access to the trade sections.
DIY Moderator is for moderators who do not have access to the trade sections (currently only ban-all-sheds)
Moderator is shown for all moderators (except for global moderators) in forums they moderate (and for some strange reason thier post based group is shown below it even though its hidden everywhere else)
Administrator is for those with total power over the forums (like me
)
Global moderators have moderator privilages everywhere.
I think thats about it.