Get PoA on Y!MMisc
Yahoo!Messenger has added a Prisoner of Azkaban IMvironment, which should be up here later today. For now, you can download it via Yahoo Messenger's INSIDER page, which pops up when you launch the Y!M program.
Special thanks to Kristin and Lozzy who discovered that if you type in the first or full names of the trio or, for some reason, "Hahahahaha" or "Muahahahaha", the YM window lights up. Unfortunately, nothing happens when you type in "Dementor".