WordPress Plug-In of the Day #0052
Title: Twitter Avatar Reloaded
From the author:
Twitter avatar reloaded Plugin adds a new field to the comment form to get the user’s Twitter usrename and stores it together with comments and using it replaces gravatar with twitter avatar when the comment is displayed. This Plugin works seamlessly and you don’t need to edit your theme files to add the new field to the comment form. It automatically adds it when activated.