I have got 2 Litter-Robots http://www.litter-robot.com/default....1?source=ysm01
and I LOVE THEM!!!!
No more scooping litter, no smell and easy to clean! They are a little expensive, but well worth it! All 6 of my cats took right to them and stopped using the regular hooded litter box, before I removed it. All you do is open the tray when it is full, remove the 13 gallon trash bag and put a new one in!
Here is a forum that talks only about Automatic Litter Boxes http://www.litterbox-central.com/forum/
They talk about all of them on the market, both the good and the bad.