have You seen a demo from www.theproduct.de ? It's really amazing. (There are 4 demos, 3 in 64kb (they are really long, have many textures and so on (program will take 200 mb of ram during playing) and 1 in 8 mb).
In the biggest demo (8mb) there is a Full Screen Glow Effect.
Does anybody have an idea how to implement something like this?