MS paint adventures

A good example of an interactive narrative is Homestuck which is part of the MS paint adventures series.

http://www.mspaintadventures.com/

The comic is set out like an interactive adventure game and parodies a lot of RPGs and text adventure type games. The comics are written and illustrated by Andrew Hussy and over the years have developed a large internet following. Homestuck is definitely the most well known and a huge fan community has grown around it.