There is some research to show that a "real world feel" is a critical component of a website (from the "What makes a website credible" study from a few years back. Having a picture of you will go some ways towards doing that. I put my pic on my website.

If you do this, please make sure to put a good pic up -- no self-taken camera phone bluriness, please. Remember, you want to personalize the experience but still seem professional.