You need two things:
1) A USB Drive devoted to this
2) The programs and files that I will show you how to make or where to get. If you have trouble making the two files that I show you how to create, they can be downloaded at the end of the Instructable.
THIS AUTO-HACKING USB DRIVE SIMPLY CONTAINS APPLICATIONS THAT RECOVER PASSWORDS AND SUCH. STOP LEAVING POSTS ABOUT HOW YOU DON'T UNDERSTAND WHAT GETS HACKED.
Step 1: A Brief Explanation
Step 2: The Autorun File
This file is the one that makes the pop-up window when you plug in the USB Drive. You can use this on any USB Drive, even if it has U3 on it.
Open Notepad (I'm using Notepad++) and type the following:
label=(Name you want the drive to have)
open=(Batch file we will make later).bat
action=(What you want the action to be)
MAKE SURE YOU DO NOT TYPE THE ()'s! Where it says (autorun), replace the parentheses with brackets (the buttons to the right of the "p" key on the keyboard. USE THE BOTTOM BRACKETS, NOT THE TWISTY FRENCH BRACKETS!)
Save this file as Autorun.inf
Make sure that you save it immediately inside your USB Drive, not inside any sub-folders (My Computer, Autohax0r).
Also, I have used an icon (an .ico file), so the USB Drive will have a different picture than the boring standard picture. To get one of these, I advise going to http://www.iconarchive.com/ to get an .ico file (you have to specifically download it as .ico). If you do this, save the icon in the same place as the Autorun file.