So maybe a page with short explainations such as:
Jahewi's CMT Group: This is an open group. This group discusses Jahewi's Canned Management Tool. It is open to Freshmen and higher. To join this group click >here<.
Trained Registry Editor: This is a closed group. This group dicusses ??????.
It is open to Members who have completed an optional windows registry training course. To join this group click >here<
This way we would know what groups we can join and at what level