MakeHuman

MakeHuman is a free and open-source tool for generating humanoid characters with detailed adjustments of proportions and other body/facial features.

"Project Maiko" (!) by Colin Barton is a good example of how MakeHuman can be used to generate a medium-poly character well-suited for renders or in-game use. The full list of updates/tutorials under the Maiko project is HERE.

A recently developed alternative to MakeHuman is Manuel Bastioni Lab (developed by Manuel Bastioni, a former user of MakeHuman). Unlike MakeHuman, MBL exists only as a Blender plugin. It features new base mesh topologies, as well as a muscle rig for more advanced deformations. Facial animation and "proxies" (alternative topologies) are currently in development.

Another good alternative is Fuse.