If you are looking for dual duty furniture, the Hydra Table does it and makes it fun at the same time. With a solid pedestal base and a simple hydraulic lifting mechanism, you can go from coffee table to dining table in moments.
We have used Hydra tables in one of our episodes of Mission Organization to great effect, and found that even if you don't need to raise your table that often, you'll do it anyway to show guests...
These tables come in many variations with tops in glass or corian, bases in wood and steel, and sizes from cofffee table to bar table in different diameters. Available starting at $1300 from Hydra Designs and at the D&D building.
(ReEdited from 2004-11-29 - MGR)