The Galaxy S and its variants, the Captivate and Vibrant don’t have the LED notification light that most other Android phones have, so a missed call or text or email won’t be noticed till you actually turn on the screen and look. But a helpful hacker over at xda-developers whipped up an application that makes use of the screen as an indicator. When the AMOLED screen displays black, it uses no power, so only a few pixels in the upper left hand corner of the screen are used to display and moving red square.
It’s a beta application, so it may not work correctly all the time, but he has already release several updates and fixes. Visit this thread at xda-developers for more about the application and a download link. And of course you can contact the developer and report issues there.
Here’s a quick video showing the NoLED in action:
***UPDATE*** Just for the heck of it, I tried it on my MyTouch Slide and it works pretty well. Although I suspect it may be using more power to turn the whole screen on.