In my forums I allow for the users to edit a post for 1 hour and do not allow them to delete their posts.
As far as deleting an account I made a group called suspended and all the permissions are set to 0 or -1. I then wipe the account information and change the email address to one of my crap email accounts, turn off all notifications, and remove their avatar and just leave their name associated with their posts. I only do this if the user request their account deleted.
For permentaly banned users I pretty much add them to the banned list, put them in the suspended group, and turn off all notifications to their account. I only ever had to ban less than 12 people since 1998.
I like this idea a lot! Its quite a bit of work, but it keeps a good "paper trail," while giving the end user what they want... need
so people can't claim some weird privacy issue or something because I refuse to delete posts or accounts, I'm not legally obliged to do this in any way am I?
I suppose some "googling" could be done on this topic, and you could form your own set of rules. Different countries handle things differently depending on where your "business" is based out of.