
I found an awesome source for 360 degree panoramic high quality sky images

All you have to do is download the image and resize it (I use 1024 pixels by 512 pixels size via Adobe Photoshop CS3, with "Nearest Neighbor" resampling), save it as a .tga, open your ###.sky file and change the DomeModel bit to point to the correct image:
DomeModel()
{
Geometry("skynamehere");
}
Here is the site:
http://lfgrafix.com/grafix/C3DB-Skies/S ... sic-1.html
http://lfgrafix.com/grafix/C3DB-Skies/S ... sic-2.html
http://lfgrafix.com/grafix/C3DB-Skies/S ... ium-1.html
http://lfgrafix.com/grafix/C3DB-Skies/S ... iFi-1.html
http://lfgrafix.com/grafix/C3DB-Skies/S ... ent-1.html
and more on the site

Usage License:
Continuum3D Free Sky Maps
These images are intended to be mapped onto a sphere or dome.
You may use these images freely to create artwork and or animation.
You MAY NOT resell these images in anyway shape or form.
You MAY give these images away on your own site, so long as you credit this site and link back to us from the images on youe site.