I was browsing around today and came across this neat effect that makes the bottom look like it fades out to the background colour. I don’t know if I would ever use something like this but I like the effect. It uses a PNG image with an alpha layer positioned in a DIV tag at the bottom of the screen with a high Z index. You would have to do some trickery to make Internet Explorer 6 play nice with it since Internet Explorer 6 does not render alpha layers in PNG images properly.
Check out the demo here. You can also download the files to play with yourself.