Originally posted by Placebo
Well, theres the NovaDreamer (or something like that?) which shines a light in your eyes, when it detects REM
You learn to associate the shape of the light to be a dreamsign

Other than that, you could schedule a quite sound to play on your PC after 6 hours of sleep, every 10 minutes
I tried this, but had to use earphones.... not comfortable
Bet your wife thought you were insane going to bed with headphones on?