Here is a great article from the eLearning Guild on avatars. If you are not familiar with the potential of avatars for e-learning check out this article by Raj Sheth titled Avatar Technology: Giving a Face to the e-Learning Interface. The article does a great job of defining avatars and describing the different types of avatars and provides examples of how they are used in a variety of settings.
Raj describes an avatar as:
An avatar, in the broadest sense, is an image that represents one party in an interactive exchange. In some situations, the avatar may represent an actual human being, but in e-Learning, the avatar almost always operates as an agent of the e-Learning application, and generally simulates human activity. Avatars in e-Learning are somewhat similar to avatars in online games.
Raj believes that avatars are just begining to show their potential in the world of e-learning. If you have some time, check out the article.