For the last few days, I've been having a lot of fun playing around with Celestia, an open-source 3D space visualization program. I've gotten the Jupiter and Saturn systems working just fine with NAIF spice kernels, got all the moons rotating correctly, and so on. Now I decided to play around with making a bump map for Io. You can see the state of this bump map at left, implemented in Celestia. I got most of the paterae in this area looking about how they should. The mountains take a little more time and require a lot of hand editing. I'm not quite satisified with the blocky appearance of the mountains, may have to try some smoothing.
I am also a little concerned by the way it shows mountains and other topography. Mountains are visible way to far around the dark side of the terminator (these things aren't that tall). They are also way to visible at low phase angles. But at phase angles like that above, I am pretty happy with the results.