How do you manage your leads?

I’m curious to know how you currently manage your leads. Do you use lead management specific software? Do you pay a monthly fee to a lead generation company who then manages them for you? Do you rely on Microsoft Outlook to store all of those prospects? Do you solely use your PDA to keep your leads’ details? Do you write numbers down in a plain old notebook and keep it with you?

What are you doing to retain each and every potential client that contacts you on a daily basis?