I found a site of "Choose your own adventure" games playable online. The code for them can be downloaded so you can make your own, and they'll even host the game for you and give you some of the ad revenue.
I recommend Choice of the Dragon, Choice of Broadsides and Choice of Romance. Choice of the Vampire was too complex, and the games made by other people... I played three of the four available and they sucked. (FAKE EDIT: Ok, now I tried the fourth and it sucked too.) But try Choice of the Dragon if nothing else.
Remus: Harry... I'm a werewolf.
Harry: Are you fucking serious?
Remus: Well yes, but I don't see how that applies here.