These are the rules that I have always used playing Shithead. There are many variations possible, so this might not be exactly how you are used to playing the game.
This online version of Shithead was made by me. My name is Einar Egilsson and over there on the left is my current Facebook profile picture! (Maybe I shouldn't have put my picture so close to the 'About Shithead' headline! Oh well.) A while ago I wanted to learn how to make simple browser games, Shithead is my favorite card game, and so that's what I made!
Since I have no artistic talent whatsoever I used graphics that I found at OpenClipArt, a great site with free graphics. The excellent playing card images were made by Nicu Buculei, check out his site for some more examples of his work. He has lots of great free graphics.
This is version 1065 of Shithead.