Chrome: Received an mail from someone you don't know? One easy way to look up information about them is to instgall Vibe and just hover your cursor over the email address.
Vibe is a lot like Rapportive, but with a few differences. First, it isn't restricted to the inbox alone, it will work across your browser anywhere that an email address is detected. Second, it's not limited to a single email address in a message.
Once you have the app installed, hovering your cursor or highlighting an email address will display a drop-down pane from the toolbar with all the details you need about that person: profiles on different networks (LinkedIn, Facebook, Twitter, Google+, and even a web page they are most likely to be associated with), a short description, and keywords that best describe that individuak.
In most cases, the information it showed me was accurate but Vibe isn't smart enough to cross-reference a person's work and personal accounts. Still, it gets the job done for showing you a quick information pane about most people.
Vibe (Free) [Chrome Web Store]