This is another one of those things that I assumed vBulletin, "the most popular discussion forum on the Internet," would be able to handle without a problem. From what I can tell, it does not have this option!
I can understand why some discussion boards would not want this due to server load, but I'm very surprised to see that it's not even available. I'll keep researching it to see if I can find a solution, but we may be screwed on this one.
Any other vBulletin users ever seen this or have any ideas??