I wrote recently about wikipedia and why I had never contributed (too wiki-ish, too much effort, not enough recognition of expertise).  So I was pleased to see this survey from Wikimedia which tries to find out “why scientists, academics and other experts do (or do not) contribute to an open collaborative project such as Wikipedia, and whether individual motivation aligns with shared perceptions of Wikipedia within expert communities”.   If you do (or don’t) contribute and have ever thought about this, do let them know.