How do you remind yourself?

How do you remind yourself about deadlines, birthdays, anniversaries or other important events in your life? We all have our individual methods, don't we? All sorts of tools come to mind - the good old-fashioned diary or organizer, electronic gadgets such as the PDA, etc. I wonder what methods do insurance agents use because they are so good at following up with their clients be it term insurance, auto insurance or medical insurance.