Exactly, I've always loved the idea of a freemium model as it gives you the best of both worlds, the ability to scale your product uptake exponentially by removing the "penny barrier" but also having a direct method of success by providing extra value to those customers who want it.

This is probably the same business model I'll be using for the startup I'm planning to apply to YC with later this year. I'm still looking at some of the numbers for other possible solutions before I make a decision either way, but right now it seems to be a win/win situation.

Now if only I could find a reliable co-founder... :(