Quad Remesher, a new auto-retopologizer from the developer of ZBrush ZRemesher, is now available for Blender!

Quad Remesher is described as a cutting-edge auto-retopologizer with smart placement of edge loops and singularities. You will get a mesh that is suitable for smooth subdivision without artifacts, proper UV mapping, easy rigging, optimal for Multiresolution sculpting.

Quad Remesher is said to work on any kind of mesh topology. "t looks at surface characteristics like concavity, convexity, and branching, then strategically places edge loops and (as few as possible) singularities," states the developer. 

You can learn more and get the plug-in here.