I just use whatever kind of latex paint is the cheapest. The little sponge rollers that are used for edging work well for applying it. Normally takes me 3-4 coats.
I sponge painted one of my tanks before to give it a little more of a texturized look. It turned out pretty cool. With specialty techniques like this, just remember to paint in the opposite order you paint on a wall. In this case sponge paint first, then paint the solid layer on afterward.