I'm a freelance iPhone programmer and I end up generating new leads fairly often from the applications I've done. Before I implemented this system I completely forgot about one potential lead / client for about a month, now however, RTM reminds me every two weeks to follow up.

Essentially I have a list "iPhone Business Contacts". The task name is the company or individual who has contacted me. Each task has three notes attached to it, Contact Information (which I can pull up on the iPhone app and dial or email from), Status (where I log the history of the lead, what I've quoted them for an hourly rate, whats been done for the client etc) and Ideas (which are basically my sense of how their application will pan out, or any of the ideas they've mentioned to me).

If its a hot lead, its a priority 1 task, and I constantly run through my list to make sure I'm following up with as many leads as possible.

Hope this helps!