-Paperclip in the reset hole. Also called a Soft Reset. No data is lost.

-Do a soft reset, and hold down the Power button. This is a Hard Reset. All data is blown away after answering "Yes" to a confirmation prompt.

-Do a soft reset, and hold down the Up button. This will do a Soft Reset, but will not execute the startup code of the installed applications. Sometimes a badly written program will refuse to be deleted from memory- doing this reset will let you pry it loose from your Pilot.