you should really think about buying Fractal Terrains from Profantasy. It will automatically generate planets for you very much in the style you've shown. You can play with various settings and easily make ice planets, foresty looking planets etc.
And get wilbur too. You don't have to be an artist to get those. Just be a little intuitive and mess around.
While I may resort to using this program in the future, my hope is that someone may be interested in working on this project before I do resort to developing it myself since I am currently programming Ruin Regions alone and I'm artistically challenged. If someone does find this project/request interesting, I hope the "Unpaid" status does not deter you too much and if it does, please let me know and we could discuss this issue in more detail.
I'll offer my standard suggestions on the topics of Fractal Terrains and Wilbur:
http://www.ridgenet.net/~jslayton/software.html and go to the "Main Program Download" link. The Fun With Wilbur links are useful.
And never overlook the message tags option under advanced search here on this forum. The tags "Wilbur" and "Fractal Terrains" will both yield a wealth of information on their respective subjects.