This might not be such a fantasy as you think it is. Yes, it will be very unpolished. But you can get the basics in place in a couple of hours: login, questions

This might not be such a fantasy as you think it is. Yes, it will be very unpolished. But you can get the basics in place in a couple of hours: login, questions, answers and voting. I agree though that to get it to the level of stackoverflow will be very hard indeed in a weekend ;)