Along the lines of the "picking up domains just because" like of thinking... I used to run a website that got a fairly decent traffic load - up to 1000 hits a day w/o the forum. Our sponser was a guy in Australia and for some reason he went MIA for about three months just a bit before the renewal came due. Naturally, someone snatched it up and has since refused to return the domain to us for less than a couple hundred bucks.

Even if it's legitimate business, people doing that piss me off.