http://www.mspaintadventures.com is a webcomic created by Andrew Hussie. It's based off of an old style text-based adventure game, readers type in "commands" for the comic. The commands then get looked over carefully and are selected based on a rather exacting set of standards, such as whichever one seems to capture the most striking intersection between cleverness and idiocy. Or, whichever the hell one they feel like picking. The picked command is then drawn and the story continues.
The site contains 3 adventures so far, only one is actually complete. The first adventure was jail break followed by Bard Quest and Problem Sleuth which is now the main story.
This site is recommended to anyone who likes web comics and doesn't mind spending a couple of hours reading Problem Sleuth (Its that long, but a save and load is provided.)
Except from MS Paint Adventures:
You are one of the top Problem Sleuths in the city. Solicitations for your service are numerous in quantity. Compensation, adequate. It is a balmy summer evening. You are feeling particularly hard boiled tonight.