I wanted to let you know about a new WordPress plugin that I wrote. It is called Ravatars, and it will generate and assign icons to the visitors leaving comments at your site. The icons are based on email, so a given visitor will get the same icon each time they comment. It is easy to customize the avatars so that they match your site's theme. A hiking blog might want to have nature-themed avatars, or you might choose to have avatars that match your blogs color scheme.
You can download the Ravatars plugin here.
Give it a try and let me know what you think.