For those not in the know, a Gravatar is an image that represents your email address which can auto-display next to comments on blog posts etc that you may make. 

Well, actually, that's just an 'avatar' - what makes a Gravatar special is that the image is remotely hosted and manageable on a website - so you can login, change your image and have it automatically instantly be changed on the gajillion websites you've posted on.

In Drupal 5.x the Gravatar module works pretty easily using Drupal's user picture support; install the module, enable picture support & gravatar user permissions and off you go - if a user on your site (registered or anon, depending on the permissions you set) has a Gravatar account their picture will display next to comment posts.

Try it out - get a Gravatar and then post a comment on this blog!