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.