Most doors would deform, they're made with very thin and unsupported (when on their side) wooden sheets.
I think, if I had room for it, I'd do one of those tables with the wings that fold down. I can't find the youtube video for the one I'm thinking of but there's a thread I found that has a similar one, to give the idea.http://www.dakkadakka.com/dakkaforum/posts/list/299849.page
Wow...no, as I try to verbalize the differences I realize that's really not that close to what I'm thinking. Gosh, ok, here's something closer, just think longer flaps/wings on the sides with legs that folds under:http://www.sears.com/shc/s/p_10153_12605_00852915000P?sid=IDx20070921x00003j&srccode=cii_9324560&cpncode=00-10622207-2
Basically, that's it, could have multiple shelves and wheels to roll around for storage (plus the previously mentioned longer flaps/wings on the sides with legs that folds under). Although, if you wanted a max 4x8 it would need to be about 3x2 when all folded up, which is lots of real estate. BUT it would store some supplies underneath saving space elsewhere and it could be used for all kinds of gaming, entertaining, etc, so the space would be well spent.
You can always make multiple boards to put on top of a real folding table or sawhorses, if you wanted various boards to play on (think I'd just keep them flat and have various terrain to change it up). Couple options from Canadian Tire regularly go on sale
for cheap, table goes for $35 or $40 and the saw horses for $10 each (need 2):http://www.canadiantire.ca/AST/browse/6/Tools/WorkTablesVises/WorkTablesBenches/PRD~0570035P/Mastercraft%252BMetal%252BSawhorse.jsp?locale=enhttp://www.canadiantire.ca/AST/browse/6/Tools/WorkTablesVises/WorkTablesBenches/PRD~0570035P/Mastercraft%252BMetal%252BSawhorse.jsp?locale=en