Another of those why-didn't-I-think-of-it-first ideas, the Picture Table is an attractive wall-mounted poster frame that ingeniously folds down to turn into a small dining table. A Murphy table, if you will.
The original table is produced by an Italian company (and is presumably not available online), but this is one idea just begging to be hacked. With a few supplies from the hardware store - or possibly IKEA's table component collection - you should be able to whip up something similar for your own space.
Now go forth and hack!
See more clever solutions for your small space.