I don't know if you were looking for information on dwarf or full size hamsters. But I have several dwarf hammies. We rescued a family of them back in 2003 and I have found by far the best habitat for them to be the hamster cages made by lixit. As seen here.(which measures 13"x20")
I have used several cages and would not recommend the habitrail type cages one of my dwarf hamsters got his teeth wedged on the bars and was found making an awful noise dangling from the top of the cage. Luckily we found him soon after he got stuck we had to cut the bar in order to free him. He was fine but it could have been nasty.