How to Launch a Free Product

Free users come to a product for a very different reason than paid customers come, right? And they'll even give you different feedback as the type of features that they want. There's no way that was your long term plan though, because how do you make money with a free product? I'm sure you're, at this point, just hemorrhaging money. How did you guys decide that launching with free was a good way to go? And what was your plan for how you would eventually start charging?