For the moment this sounded me like a Dropped (I think) Mod "Advanced Rules and User Agreement Hack" that was one of the Most Outstanding Rules Hacks I've seen, and it had most of the features that other Forumers are Asking you for, and is that the Users have to Agree and that Agreement is Saved on the DataBase (and if can be shown on their Profile the Rules/Conditions of each Forum that they've agreed you're one Step Closer to Offer that Great Advanced Rules Mod that most Forumers are waiting to Use).
If you see the Agreement to Post a Thread is related with the Agreement to Access/Post on a Forum, and you can offer the possibility for Admins to Create Rules for the Forums They Wish and Users should Agree to them before Posting and Even Accessing those Forums. If you search on Internet you'll be able to Find the Last Version of that Mod that was Developped for vB367 (if installed on vB368 it doesn't work, I tried to Play with the Code and managed to make it create the table for Rules but I couldn't figure another Error related with a SQL Sentence); that Mod is Currently on the Graveyard and Dumped for so long now, but I think it could give you some ideas for you to Improve this Mod and that Many Forumers would Appreciate a Lot if you can Develop it and even Improve it with your Coding Skills.
I Hope You Can Share That Kind of Mod.
My Best Regards.