I'm writing a site in ASP.NET MVC that will have user accounts. As the site will be oriented towards discussion, I think I need a system for admins to be able to moderate users, just like we have here, on Stack Overflow. I'd like to be able to put a user into a "suspension", so that they are able to log in to the site (at which point they are greeted with a message, such as, "Your account has been suspended until [DATE]"), but are unable to do the functions that users they would normally be able to do.

What's the best way of implementing this?

I was thinking of creating a "Suspended" role, but the thing is, I have a few different roles for normal users themselves, with different privileges.

Have you ever designed a feature like this before? How should I do it? Thanks in advance.