Forum Moderators: not2easy
2) That the users certify a certain age, usually 13 or something.
3) That they should be respectful against each other.
4) No spamming (if you don't want it of course)
5) That you can terminate their account and remove posts as you see fit (or something similar)
6) Your site is protected according to different copyright acts (depends on which country you are in).
There is probably a bunch of other disclaimers, you will have to be more specific. It's often good to get hooked up with a lawyer if you are planning on something big.