Meshlab
Meshlab is a special type of program that helps process unstructured 3D models and meshes that come from 3D scanning. 3D models tend to get very large, but the Meshlab Development Team has built a complete set of tools in the software that will help with editing, converting, rendering, inspecting and otherwise do some touching up. If you've ever used a 3D program before and had problems with mesh editing, this can really help.