I have archived some examples of past games enjoyed on the official Warner Bros message boards for Slytherin House:
Harry Potter Pants Game
Harry Potter Hoedown
(Oh, and don't think I haven't noticed that certain people have used these games as an opportunity to insult me!)
If you are inspired by this drivel and want to submit your own poetry, or even fancy dabbling in some dodgy pants, you can go to the official Harry Potter site or have your efforts mounted by the Project Potter website.