Thanks guys! It seems that my problem was the density. I had really high density, since the clouds I have made before and looked on from ground level turned out better then. Now I know that the density should be really low from space.
Seems that my sphere vanished though... it was still there, with the same settings and all, but nowhere to be seen. I haven't worked with objects before, so not sure if this is a known bug...
Anyway, the clouds are better now, as you can see! Could be a lot better, but it's a vast improvement, and all I really did was to give it a bit more depth (I plussed on 500 or so) and I increased the altitude. But the most important thing was changing the density. 'cause it was about 0.05 or so...
Oh, and yeah. The bright white on the planet is the snow created with the Planet Shader. I didn't do anything with the planet really, just added a Fractal terrain with a Planet shader... As I said, I am still a newbie :p
And great renders guys! I especially love yours Bluefinger!