"Graph Your Inbox" a side of Gmail you probably yet to see

Graph Your Inbox is a Google Chrome extension that allows you to graph Gmail activity over time. You can use it to visualize your communication with friends, your Facebook activity, when you purchased items on Amazon or how often you use certain words or phrases. We provide the same search functionality used by Gmail, but instead of a list of messages we show you graphs of email trends over time.

Our inboxes contain a tremendous amount of information. Nearly every substantive action we take online generates email, from buying goods to booking flights to social network activity. Despite this large amount of data, extracting and graphing this information can be extremely difficult. Graph Your Inbox is an attempt to solve this problem. It was created by Bill Zeller, a PhD Candidate at Princeton University.

Note: We take your privacy extremely seriously. This extension does not save any personal information and does not send any personal information to any server. It does not request or record your email password. This extension does not modify the Gmail website or your email in any way. 

How Do I Use It? Download and install the extension by clicking the link above. Once it's installed, an icon will appear in the Chrome address bar (to the right). Click this icon to open the extension and start graphing your email. (If you have problems, make sure you're logged into Gmail.)

Download here

The extension is simple yet powerful: it runs a search on your Gmail inbox for whatever query you want, then plots it over time in an attractive graph (you can compare multiple queries at the same time). You can type and search "facebook' or any other words you want to put on graphs.

After the installation you will see an envelop( a logo of graph your inbox) at the right side of your address bar.