I have no experience with nanos but do know that you don't have to have a fuge for them. Nanos can be very simple as long as you take your time with them. All you need is some good live rock, decent light, a heater, and something for circulation (powerhead). The live rock will be your filter system along with water changes. As with all nanos, it will have to be very lightly stocked. If you don't mind the way it looks, some macroalgae in the tank would be good and you can usually find a piece of live rock with it growing on it. This will help with using up excess nutrients. Start simple with some mushrooms and such and maybe a small shrimp or something till you get comfortable with it.

I met a guy awhile back that had a 10g nano in his kitchen that just had some live rock and two powerheads in it. He kept a small puffer fish of his that had been in his main tank, but moved it after it's eyes clouded up and seemed to have gone mostly blind. It did very well in the nano and got healthier. It could see the motion of the guy when he approached the tank for feeding time. Pretty cool.