You've asked for it. Again. And Again. And Again.
It has never existed before for SMF but I finally went out and hired a 3rd party developer to make it a reality.
When in a topic just click on "Add Wiki" (it's one of those buttons just above the title bar of a thread).
You can also edit the wiki and revert the wiki to previous versions. Just click on the wiki timestamp to view previous versions of the wiki.
Click on the - (all the way on the right on the wiki bar) to minimize the wiki on page 1 of a thread or the + to maximize the wiki on subsequent pages.
For now you must be logged in to view the wiki and you must be a DansDeals Platinum elite member to edit a Wiki.
Post in this thread if you have any questions or find any bugs. And thanks for making DDF a great place to hang out!
And a huge thanks to SMF developer "Emanuele" who is a class-act in every sense of the word, and of course our very own volunteer techie, the one and only BAHayman!