Here are a couple questions I found interesting browsing around. Like I said in my comment above, I think we should try to hit the various roles people have: developer, admin, and end-user.

Developer questions:

 - [When to use OpenWeb() vs RootWeb?][1] - There are any number of SPWeb questions we could use that are good.
 - [How do you get the current list item in JavaScript?][2] - Pretty involved but interesting.

Admin questions:

 - [jQuery accordion for the Quick Launch menu?][3] - Gotta have jQuery somewhere!
 - [Sorting grouped items in a list view?][4] - Such an annoying problem but the answer is so simple!

End user

 - [Why doesn't clicking New Document save back to the document library?][5] 
 - [How do I check in a LOT of files all at once?][6]


  [1]: http://sharepoint.stackexchange.com/q/17740/2070
  [2]: http://sharepoint.stackexchange.com/q/11169/2070
  [3]: http://sharepoint.stackexchange.com/q/18442/2070
  [4]: http://sharepoint.stackexchange.com/q/27458/2070
  [5]: http://sharepoint.stackexchange.com/q/13884/2070
  [6]: http://sharepoint.stackexchange.com/q/12214/2070