Rapportive is a free extension that works for both browsers Firefox , Safari , Mailplane , and Chrome will add interesting information about the activities of your gmail contacts right on your inbox.
You should download the extension according to the browser you use and then sign up for the services you want to compare. You can add Twitter, Facebook, LinkedIn, Skype.
Rapportive shows you everything about your contacts right inside your inbox.
You can immediately see what people look like, where they're based, and what they do. You can establish rapport by mentioning shared interests. You can grow your network by connecting on LinkedIn, Twitter, Facebook and more. And you can record thoughts for later by leaving notes.
Imagine relationship management built into your email. For free.
Download: Firefox , Safari , Mailplane , and Chrome