I use Salesforce to work leads, and in the past there was a simple widget that you could use in Salesforce to connect your account to the adwords account and track where leads were coming from. Every time a visitor filled out a contact form we would have adwords data sent over and attached to the lead. We could go in and mine that data and decided what campaigns were working the best, and what keywords were bringing in the highest quality leads.
Well, Salesforce has pulled this tool(I actually think google did it to them) and now I am looking for something new.
I have read that Contact Form 7 does stuff like this, but I do not know if anyone has had any experince with it.
Francis Van de Beuken
Weight Loss Camp BalanceME