Reportive Gmail Addon
I’ve started using Rapportive to help me track leads coming in from my Aweber Autoresponders.
This Gmail plugin connects to all of my social networks and grabs information about the persons email address. If they have an account on any of the social networks you will be able to instantly friend them or send them a message.
Also lets you keep notes on each person so you can refer back to them if you are dealing with lots of people every day and have a hard time keeping track.
Overall i think Reportive is great for lead tracking in Gmail.