hmm, the other way round, i also have a good side, too ;)

Ban him, and say you saw him advertiseing a site thru private messages.

that is if you have the view pm's hack, but if you don't have it, lie and say you do.;)

You could say some members complained that he was spamming via PMs or e-mail; that way you don't need to have any hack.

The turtle has hit it right on the proverbial head.

The big-nosed Erwin has descriminated the all mighty teenage mutant ninja turtle once again! ;)

Are we looking for something a little more technical and devious than to just ban him?

You guys have great ideas but I have already done everything that I can to the extent of saying he is spamming via private messages, etc. He is well liked by alot of members, although he is screwing them over (he sells retail products to my members). So I really need some way of annoying him so much that he goes away; banning him is not an option unless he breaks the rules - which isn't going to happen IMO. He is scamming alot of my members (hundreds of young members for the most part) and unfortunately they think he is a great guy - and keep spending their money with him. He is a plague on my site and I need a tricky way to get rid of him, because conventional methods are not working. More thoughts are appreciated!

If he's spamming ban him. If he doesn't like it then tell him to either piss off or pay for the vBulletin license, hosting, and domain name. You could also use the ignore hacks where he sees his own posts but nobody else does.

go to your acp n keep resetting his status as not logged in...

That involves being online the same time and being very pesistant.