uses Gravatar to fill in profile images. 

Gravatar is a free service - users can add their image in one place and any website that uses gravatar will automatically fill with your image. It saves you time! It works with Wordpress sites too, any time you want to comment, simply log in with your wordpress/gravatar account.

Here are the instructions on how to set it up. Make sure you add the same email you used to log in with on!

Go to Instructions on Gravatar's Support Site