Just messing around with light settings. Should’ve been obvious I guess but you can make color just by changing the light settings…no materials, nada.
Check 'em out:
Mmmmmmm, sherbert! 
OK now take a model add a yellow sun or area light then add a dim blue hemi light opposite and you have some daylight shadows.
TADA!!
Try it
If you are underwater add a veroni texture to the sun and use mist in the world settings.
lets see some more examples with something a little nicer than a cube at least bevel it and create a ground plane.
Sorry about the snappy post :o
here are some pics with light effects.
Underwater
settings
Sorry about the snappy post :o
No problem, I didn’t think it was snappy; but maybe it was…forgiven 
Wow, that’s awesome!
Is that a random texture you can generate in Blender or not?
BTW, are there two lights there?
yes its a voronoi tex. If you look at that really jumbled screen shot all the world and lamp settings are shown. And no I don’t work with Blender set up like that.
The settings for the second lamp a hemi are not shown but its pale blue,low power and opposite the area lamp to light the shadows.
Sweet! Thanks!