Although this isn't cheap, ultra short throw projectors like this
http://www.lg.com/us/home-video/lg-PH450UG-projector or the new Sony product can be placed on a table as an ad-hoc presentation or gaming surface. Unfortunately they are hard to get in Canada, but I ordered one from Amazon US yesterday which should show up next week.
I would expect in the next couple years these will become more popular and easy to get. They have the definite advantage of portability, so you can just take it anywhere. I intend to use it for tabletop gaming so I'll report back on how good it is for the purpose if anyone is interested.
PS: This is the Sony one, which looks a bit nicer but is also $999 US list price.
http://www.sony.com/electronics/projector/lspx-p1