I agree that you need to keep a direction for SE, but there is one type of open-ended conversation starters that often works really well there - the list. E.g "

I agree that you need to keep a direction for SE, but there is one type of open-ended conversation starters that often works really well there - the list. E.g "What feature would you like to see in C++15 (or whatever the next one will be called)?", "What is your favourite bit twiddling trick?", "What is your favourite language outside the TIOBE top-20 and why?", etc. With one list item per answer and the help of the voting structure, those tend to produce interesting reading.