I just took a look at the Rapportive Rich Contact resource add on to the Chrome browser. It works with the GMail service only. It will not work with the Explorer browser, but will work with Firefox. It replaces the advertising column in GMail with information about the email message sender you click on or mouse-over. It looks up the email address of the person and provides whatever it can find, including their picture, Linkedin profile, social media activity, etc. You can also can add your own private note about a contact.
A very nice idea, especially if you have very many contacts that are also dynamic, as I do. Very useful to have it all in front of you. When I used it at first it could not find a number of my contacts, but indicated it would continue to search offline. I will check again later. This is only good if you nearly always get useful results. Worth trying.
Update: Their CEO Rahul Vohra quickly comments ... Thanks for bearing with us! We can take a few days or so to find social links, and we're improving our systems all the time.
See also more on the company in Readwriteweb.