General :: Amoled Clock When Screen Is Turned Off?

I've got a Nexus S phone with an amoled screen and I was wondering, is it possible to make it so that when the screen is turned off, a clock appears on the screen?

I remember some nokia phone that also had an amoled screen and that had a neat feature; whenever the screen was turned off, there was an always-on clock that'd show up, and since the clock was small and the rest of the screen stayed black, it didn't drain the battery.

I mean, that'd be a pretty cool thing to have on amoled android phones, no?