Quick demonstration of adaptive topology sculpting based off the paper "Freestyle: Sculpting meshes with self-adaptive topology" by Lucian Stãnculescua, Raphaëlle Chainea, and Marie-Paule Canic.

http://www.sciencedirect.com/science/article/pii/S0097849311000720.

The code is available from Gitorious (in the adaptive branch): https://gitorious.org/~nicholasbishop/blenderprojects/nicholasbishop-blender

See also this post: http://code.blender.org/index.php/2011/10/dynamic-topology-sculpting/