The itouchless Sensor Flush fits into a standard toilet and has a sensor built into the handle. The optical sensor will detect when the user steps away from the toilet and will flush it automatically. The handle still works to manually flush. Runs off batteries. They are selling it for $99 now, normal price is $199.

It's on my list. These are the same guys who make the automatic paper towel dispenser I blogged about awhile back.