Using a spam-trap e-mail address with greylist

Is anyone doing this?


Say I make up a new, bogus user for our domain and post it on various web 
pages, online sites, newsgroups, etc but never use it for mail. Then I would 
automatically black list any IP that sends an e-mail to that user since it 
has to be from a spammer.

Can it be done?  Worth the effort?

Just wondering,

Dennis