Is there a hack that will take mail going to a specified e-mail address (say, vbulletin@mysite.com) and create threads on a bulletin board under a pre-created user (vbulletin, for instance)?

Would love to find something to do that, if it's possible.

Nope.

There has been significant discussion about that very thing here over the last couple of months. I'm sorry I didn't search out the thread, but judicious use of the search engine should locate this for you.

-t