My washcloth corner hammock can seat my two girls together in rat-pile fashion. It may only fit one rat, though, if it's a big boy :)

I use a cheap or old washcloth for hammocks. To the left is a step by step illustration of how to turn a washcloth with a dowel rod and three saftey pins into a corner hammock.

1) Fold the washcloth in half, diagonally. Where the two corners meet at a point is the tip of the triangle that will be pinned into the corner of the wire cage.

2) Insert the dowel rod along the folded edge to provide a support. I drew a biggie-sized saftey pin... hehe.

3) Pin the two corners together to the wire frame of the cage in the corner you wish. Then, wedge the dowel rod's ends against the bars along the walls, and pin both of the washcloth corners against the walls as well, to keep the washcloth tight. Add rats.