What is the right price to charge? Is it $0.00

I am currently reading "Free" by Chris Anderson. It talks about how price for online services tends towards zero due to the very low marginal cost of adding additional users. I was very interested to read about the huge psychological gap between paying $0.01 for something and paying $0.00 for something. If you are currently thinking about a pricing strategy for an online service then I would very much recommend getting a copy of the book.