If you really want to be public in your telling-offs (or you're just really sick of the whole social networking thing), check out Snubster. Sign up, set up your profile, and submit your list of people you want to snub:

These lists can contain items or people. If you choose people, supply an email address to identify the person. The email address will remain private, but we'll send them an email letting them know that they're either on notice or that they are now dead to you.

There are just soooo many reasons why this is such a good idea!