Hello all,
A while ago, myself and Frazzle attempted to make a 3dgs example of the idea posed in the paper:
http://es.geocities.com/kenchoweb/skydomes_en.pdfIt was for our upcoming project

, but we decided to change methods and we no longer needed it, so we decided to release it in case anyone else could use it

.
It's basically a method to colour a dome to look like a sky (obviously ^^) using a gradient map, and a simple shader. It looks good, and has the same look as Atmospheric scattering (without the Sun visible).
The basic idea is you have an image, and in that image is (horizontally) the phases of the sky, from night, to sunrise, to day, to sunset, to night time again. And vertically is the altitude.

And here is what it looks like:

The beauty in it is that it is very small, one 64x64 image, and a few maths operations

LINK (A7):
http://www.megaupload.com/?d=A3B9OE8MLINK (A6):
http://www.megaupload.com/?d=DVX5X2UVEnjoy

Frazzle and Adoado