Open Question: portable bunkbed cots?

I am looking for a way to make more floor space in a tent without having to get a bigger one. I have heard about the disc o bed bunk bed cots but was wondering if there is another company that makes bunk bed cots. Or if there was a way to make them stackable.
I just want to see my different options

Source:
http://answers.yahoo.com/question/index?qid=20110808184709AABGNKS

campground reviews airstream campgrounds camping campgrounds target camping locations