>I have a little program I'd like to try and sell. I am interested in having a 'key' or some method to stop it being passed from person to person without receiving payment. What is the best way to do this?

This's how I protect my apps (Fpd 2.6 DOS + Visual Foxpro):

-When my application first installed a new machine it warns user about "demo mode run".
-If user choose run in demo mode there's a record limit with demo mode.
-If user choose licensed customer mode it shows a random key at screen, than customer calls me and give that key, my key generator generates a unlock key and customer enters this unlock key. Application generates different keys every time so an unlock key valid for just one time.
-After validated unlock key, my application generates a hashed file, it contains some information about pc (HDD serial, mac id, cpu serial...)
-If user copy application or change parts about configuration file, application changes to demo mode.

I have 300 my own customers and thousands customers of company which I worked for and didn't see any customer cracked yet. Of course if my applications would be more popular cracked yet... :)

I pack my VFP applications with Molebox for piracy.

I don't advice any of hardware dongles. There are instant ready-crack utilities for all of them.