If you are interested in trying out interactive writing (either parser or choice based) but you don't know where to begin, then this would be a good starting point. Personally, I would add ChoiceScript to the list as well, even though it isn't open source (but neither is Inform7). Hmm... could a nice article of my own, but I digress.
ChoiceOfGames publishing model is almost perfect as it gives everyone the necessary tools to produce high quality choice-based IF and a range of publishing options from fully commercial under their flag, down to do-with-it-what-you-will and deal with monetization and promotion yourself. I might write a full article down the line what a fantastic model this is for game and content creators. I might not agree entirely with their editorial policies for their flagship label but hey it's their own thing... but more on that later, perhaps.
