Gmail users are used a lot of little add-ons that make the experience of regular email much richer than other web-based solutions.
At the same time, they are used to the slew of ads that pop up in the right hand side of the page. While blended into the experience, it's still advertising.
Why not remove the ads and replace it with social content related to the sender of the email you're reading?
That's the premise behind a new tool making the social web rounds called Rapportive.
The service is billed as a simple CRM tool, built into GMail. What it actually does is replace the sidebar where ads are placed with biographical information of the email sender in the form of social networking links, i.e. the person's Twitter feed, Facebook page, LinkedIn, etc.
It's easy to install — one click — and just requires users to "grant" it access in Gmail to access your name and email address — probably through your Google account. Rest assured, no private data is shared.
With Google's Buzz adds social content to the Gmail experience in a separate sub-channel within Gmail, Rapportive sort of flows through the email experience, providing useful add-on information for the user.