http://www.123dapp.com/meshmixer - A mesh mashup tool from Autodesk, some pretty cool sculpting tools too
http://www.wings3d.com/ - I just found yesterday, now my all time favorite 3D modelling program - it’s the only one I am capable of making anything with 
http://www.mit.edu/~ibaran/autorig/pinocchio.html - Auto rig meshes (with source code), would be good if could be turned into a simple UE4 plug-in (hint hint)