I've been parking about 30 domains at . It makes me a few bucks each month just for sitting there until someone wants to make an offer on one of them.
To see what one of the parked pages look like, here's a link to one of my most clicked on domain names parked at Sedo ...
I've had some offers but none that I was willing to take so far. But ya never know!
Rick Wilson aka CorpRebel