Just thought of something pretty cool. We can actually use the SDMB forum features to write a gamebook!
The idea I have in mind is to use the “View Individual Post” function (which you can access by clicking on the post-number right next to the “Report this Post” {triangular exclamation mark}). Then we use the hyperlink function to connect to the various post, and thus forming a gamebook.
Examples to follow!
The entry point to the game is here:
http://boards.straightdope.com/sdmb/showpost.php?p=10803746&postcount=1
As you can see, we can use the postcount as page numbers. We can reserve ‘pages’ in the hyperlinks, though I recommend you do it in sequential order. The important thing to remember is that you only have 5 minutes to edit your post to setup the links, so it’s a good idea to preview.
Try to leave blank options for others to follow (see the control thread if anytime we have a dead-end - if we reach a dead-end, I guess it’s game over and we can start a new story!) You can either
a) Like what I have done, hyperlink it to a post count that don’t exist yet, so that the next person come along to fill it in
b) Indicate the post-count that you would like to reserve for that option.
It’s best to try to do this in sequential order.
Remember, the entry point to the game is the “View Single Post” function; reading the thread as normal is of course a spoiler 
Have fun, and hope this takes off. there are logistic issues but I’m sure we can work those out.
You can continue writing after a post if it is sequential to add in new options and etc. Due to the edit window of being only 5 minutes, pages written in the past or more or less craved in stone.