I've tried to learn a bit more about Blender, this is the result.
These skyboxes are made exclusively with procedural Blender materials, Gimp filters and Inkscape, i.e. they are completely algorithmic.

The packets include all the source files (.blend, .xcf, ...), the skybox images (6x 1024x1024), an editorimage and a script.

Planets

http://rapidshare.com/files/296107295/newsky_planets.pk3 (12.6 MB)
EDIT: I also uploaded the terrestrial planet material to the Blender Open Material Repository.

Asteroids

http://rapidshare.com/files/296107293/newsky_asteroids.pk3 (26 MB)

Nebulae

http://rapidshare.com/files/296107294/newsky_nebulae.pk3 (13.6 MB)

(I know that some of my methods to get things done with blender are questionable, I'm still learning )

As always, some pure, quality stuff from you!

Thank you very much!

very nice. i hope to see some maps made with those

Like wow, i tried some time ago to make some nice skyboxes but i had no luck at all. I've looked at your blender file and it really shows how it should be done. Very educational, thank you.

Oh my god sev, great work! A lot of compliments! I love nebulae and asteroids (nebulae is my favourite), I've also seen your blend file: what a complicated planes setup! How the concave planes work?
WOW, thx to share!

He attached the GPL GPL V2 to the text files in these!

Needs to be included to Nexuiz!
And I'll study the source, and try to learn.

I commited. Should be in next version.

Thanks