Bunch of companies have them, and if you have 3 or more of them, you could take in 11,000 bucks for a two week stay in the hospital. I used to have 3 of them, and if I went in twice a year, i'd have fun money out the a*s.
I currently only have united american. If you wanted to, you could have like 9 or 10 of them (as long as you could pay the premiums), and then if you went into the hospital, you would take in a boatload of money.