You ought to know know that I like to try different virtual worlds. Well I've just had a bit of a play with
3DEE.
Not exactly either Second Life or There, but it doesn't seem to try to be. You download and install the client, and can then login as a Tourist. If you like it you can later become a citizen. Once you're a citizen you have greater choice of your avatar (all pre-set) and can visit more than the town square.
I decided to become a free citizen and became a duck, checking out Architecture and Animal worlds. It was simple and fun to look around. Occasionally other avatars would pop into existence, but few stayed. I suspect that as it all seems to be based in the Netherlands, everyone else is busy in the real world.