This is an older project from MIT, but I think it is still very relevant. Robotic F.A.C.E. or "Facial Alerting in a Communication Environment" is an interesting project that tried to relay human emotion via a simple, and cheap, toy. You may not be able to get this exact toy anymore, but there are plenty more just like it.
The goal of this project was to create a head that can be used to display information. The face can be a very powerful method of conveying information, and a robotic head can serve as a very useful indicator. This project is meant to provide computer programs the benefit of using a physical object in the form of a face as a means of user interaction in addition to standard outputs such as a monitor or speakers.
Read more about Robotic F.A.C.E.
http://blog.makezine.com/archive/2008/06/robotic_face.html