It's quite possible...
www.nano-reef.com and check out there members photos, some awesome ones, very small. The member of the week tank, is a 2.5 gallon.. amazing. However, I do not suggest using the 6 gallon eclipse. The 7 bowfront made by aga, is a much better tank for less money. Buy a 32 watt fixture, 5-10 pds of live rock 10 pds of live sand, a mini jet 404, and a reliabel heater, and you've got yourself a small, easy, realivly cheap setup, for less then 200 bucks.. Adding corals will be trickeyer, I suggest joining the nano-reef board for that (sorry johnny, but, there's a much wider variety of reefs over there, then over here!) and buying sum cheap starter corals. Mushrooms, zoos and polyps are great starter corals. You could get away with atleast 1 clown fish, but, I'd stick to just false or true percuals, anything more would put to much stress on the system, and no anenomes please, atleast not for a few years. Youc ould also add a small shrimp (such as a cleaner, or peppermint) and a few turbo snails to keep up with algae.. I