I actually love this site for I can ask even the most mundane questions that have been in my mind for god knows how long. So while I do think of questions that might interest fellow members, I mostly just ask whatever comes to mind.
You can also post questions, which you and your friends have been arguing with. Opinions of strangers are actually interesting, too, for they kind of lack biases.
If you like to ask pretty popular questions, I think the more philosophical rather that the technical ones are the good way to go, especially if you want the conversation going.
Nonetheless, I wish more opinion-based questions will be posted on this site because it is really quite fun to converse with people around the globe.