If you're working with the game engine or you have another reason to use low polygon modeling, then this tutorial by NeOmega might be interesting to you.
It explains how to accurately map the features of a high-resolution model on a lower resolution model by using normal maps, a feature that has been added in Blender 2.36. The result is pretty cool but be warned: there's quite a bit of work involved.
You'll find it in the CGTalk Forum.
