In this tutorial, Mathais (mamoworld.com) shows how iExpressions makes it easy to create realistic movement in After Effects. He rigs a 3D character using iExpressions on the Generator, a feature-set found in ShapeShifter AE. Check it out, it is well worth your while.
I run the website Mamoworld where you can find useful tools and tutorials for After Effects. I like teaching and my goal is to develop tools that are both powerful and as easy and intuitive to use as possible.