Just playing around with mad god's amazingly versatile Cosmic Forge Editor (don't worry; I'm not cheating by changing the installation of W7 used in the Let's Play sessions).
The Cosmic Forge Editor can be used to view and/or change the contents of game files for W6, W7 and W8. Items, monsters, text messages, loot, graphics, maps, dungeons - this program can be used to edit all of this and more. Understandably enough, CFE isn't as stable and reliable as you would expect an official world editor (such as the ones included with NWN or Morrowind/Oblivion) to be, and changes you make will often crash the game. But the program is still surprisingly powerful and user-friendly for a fan-made utility.