There are probably numerous problems/questions which at one time or another we've encountered and wished the answer existed on StackExchange (or similar) but ended up having to figure out/resolve ourselves.
With a view to building up content, especially so it can be indexed by the likes of google etc, can we perhaps come up with a list of these more complex questions, and then providing the answers (possibly getting further feedback too)? Possibly also trying to build up a list of those questions which we've often seen posted on the like of the developer.force.com forums which have standard patterns/solutions.
See http://blog.stackoverflow.com/2011/07/its-ok-to-ask-and-answer-your-own-questions/ for stackoverflows thoughts on the matter.