One of the toughest decisions is what Wiki engine should we begin with.
There are many excellent alternatives. Any choice will mean the sacrifice of the exclusive features the others might have.
After some discussion we came to realize that one very important feature for the selected wiki engine should be the existence of a plugins API or, better yet, known extensions.
Yed suggested that we build both the spreadsheets and the presentation apps over the wiki engine. It is an interesting idea, but one that makes this choice very hard.
What are your thoughts on the subject, and which are your candidates?