Your Gmail contacts can be integrated with Gravatar
With the help of greasemonkey script add-on in Mozilla Firefox you can integrate Gravatar with Gmail Contacts. Because of add-on, every individual’s gravatar icon is displayed on the left of the email ID.
This Gmail Hack is made by Jon Fox. The graver icon is displayed only while reading a single person’s mail; it doesn’t work with multiple messages. This is a whole new and fresh idea. To make this trick happen a person should have a gravatar account.
You can try this trick with your Gmail and for that you have to download the hack.