Is it possible to make a moving skybox, or clouds that move?
This pretty much does all the sky and clouds animation all in one amazing package:
http://www.pixelstudio.nl/?p=138
Here is a link to the sun light wiki page, has some stuff about changing the light and colour of the sun:
http://unifycommunity.com/wiki/index.php?title=SunLight
This one is a link to the skybox blend wiki page:
http://www.unifycommunity.com/wiki/index.php?title=SkyboxBlended
This guy is selling a tutorial all about making a day/night cycle:
http://forum.unity3d.com/viewtopic.php?t=51106&highlight=night+cycle
Hey guys i found a Great tutorial for a day and night cycle also it gets even better the dude also has a free 75 parts tutorial (and growing) on how to make a hack and slash rpg! go
This may not be the best way... but you could always store an array of skybox materials somewhere, and then slowly iterate through them (in a looping fashion, assigning each material in sequence to the camera's Skybox component), so that the skybox appears to be animating. I don't know what kind of performance that would demonstrate, it may lag and it may not, but that's really the only way I can think of, unless someone else has a better idea.
Not to mention you'd have to create the skybox textures (6 of them, one for each axis +/-X, +/-Y, +/-Z) by hand, and then animate them, saving each group of 6 over each frame of the animation, and then trying to get it to loop back around so it would blend seamlessly with the first frame... it might be more hassle than it's worth.
Edit: Just thought of an alternate way...
You could create a sphere with inverted normals (facing inward), so that the texture that's applied to it is painted on the inside, and then make the sphere really (really!) big, sticking your entire world inside of it... and then just slowly rotate the sphere. This would cause the texture that's painted on the inside of it to slowly rotate around, giving the illusion that the sky is "moving".
if you have a tiny project you can put inside an empty gameobject all your stuff (including cameras, but not the GUI obviously), then rotate that gameobject continously with a script.
The manual sphere with inverted normals is actually very usable. It’s even better if you create different spheres with clouds separated onto them so they can rotate independently.
Yes I Know how using video textures…
Create a 6 sided Sky box Material,
And load videos into each slot,
Front, back,left,right,up,down…
You can make these videos in Brcye…
Make a nice sky in Bryce,
Make required video length.
I did 10 secs.
Then set Bryce camera settings, by double
Clicking Camera track ball
Set FOV aspect to 112.5,
Rotation to 0,0,0
Go into SKYLAB and turn of “link sun to view”
And “link clouds to view”.
Set render options to a square picture,
Ie 800 x 800 …
Render the 10 sec clip as “Forward-sky”
Back into cam settings…
Rotation to 0,90,0
Render clip as “Right Sky”
Rotation to 0,180,0
Render clip as “Back sky”
Rotation to 0,270,0
Render as “Left sky”
Rotation to 90,0,0
Render as “Down sky”
Rotation to 270,0,0
Render as “Up sky”
,…
These are your 6 views, 6 videos of 10 sec views.
You can now load these videos into each slot in
6 sided skymap material.
However after 10 secs you will have an ugly loop
As the clouds will be in different places at end
Of 10 sec cycle, I got round this by using a video
Editor on each video clip and blended start & end
Frames… Not sure how to make a continuous
Cloud loop in Bryce (please tell me if u figure it put).
Well that’s how it works for me…
Have to play with video quality and maybe rotate
Up or down video view, but that’s the idea and it
Works… Good luck and please ask questions or add
Better ideas, I realize this is an OLD THREAD however
It might still help some people’s as I found myself
Reading it so… 
@jylehr its possible using a 6 sided skymap with a video for each view. You must create these videos in some 3d software like Bryce or Blunder or similar… I know how just ask or see my other answers on thread…