My co-founder and I met through his previous startup UpDown.com. I was an early user for the site and he was one of the first employees. We would chat everyday

My co-founder and I met through his previous startup UpDown.com. I was an early user for the site and he was one of the first employees. We would chat everyday on IM and he would ask me product feedback, design, new ideas, etc for UpDown. We both independently moved out to the bay area and just started working on random ideas together. It was cool because we got to work together long in advance from being co-founders and we were also friends beforehand. Personally I think its always a upside to knowing how the other person works and being in a productive environment with your potential co-founder in advance.