How do they affect you? Do you choose them to reflect your mood/persona or do you find they alter the way you feel/interact online?
Have you noticed changes in the way other people interact with you after changing your av?
This time around my choice of avatar was quite deliberate. It's supposed to send a particular message a picture by which to interpret my words.
Most usually I tend to choose an avatar based upon my mood and a mood which I wish to project with my words. This time it was more a conscious choice based on a face I wished to put beside my words.