If you have not seen the planets and satellites of Bjorn Jonsson, it is time to look. Bjorn Jonsson has highly realistic 3D renderings of planetary objects available at his website. Many of the renderings are done with a specialized planetary renderer, which he wrote for the specific purpose of creating these images. Other renderings are created with POV-Ray or by combining renderings from his renderer and POV-Ray. More information about the software and process can be found at his web page. Below are a few examples of his work.
Note: All artwork and images copyright © Bjorn Jonsson. Please do not use images without the permission of the artist.
Bjorn Jonsson's website
Bjorn Jonsson at the Unmanned Spaceflight.com