My list is too long (I keep an entire CD filled with essential utils). But here is the latest addition to my collection:
DVD Region-Free !
The name sucks and its a little expensive but its cool. It makes your DVD drive behave like its region free without messing with the firmware. This was great for me since I can't find any region free firmware for the drive I have (pacific digital). It works great and I can now watch my PAL DVD collection on my PC. It also has a few extra features like removing macrovision protection and allowing you to skip the FBI warnings.
Core2 Q9400 @ 3.0, eVGA GTX 260, 4G DDR 800, Vista64