We have been looking at possibly getting a sleep number bed to replace our soft-side baffle waterbed that's now about 9 years old. Mostly, we're considering this because of my back problems. I need a LOT more support. When I went to Colorado, my back problems let up, and I slept like a DREAM. I think it had to do with the bed. Anyway, we tried them out, and in theory they sound great, but they're expensive as all hell. I also read pretty poor reviews from some people online that it didn't help their back at all.
So today, when I was doing out 'bulk shopping' at Sam's, I saw that they had a 3" deep tempurpedic mattress topper, king size, for less than $150. If you've priced these elsewhere, you know that is DAMN good. When I got it home, it's in this 'all of the life sucked out of it along with the air' state. You have to wait 48-72 hours for it to completely bounce back before putting it on your bed. Seriously. This thing was about two inches thick, about 3 feet long and 1 1/2 feet across, and it is SLOWLY expanding in my office to become three inches deep and the size of a king mattress.
I can't WAIT to try it. I hope it gives me just a LITTLE bit more support, such that I feel better and we don't have to spring for a new mattress. :)