You have stumbled onto my all-encompassing Theory of Service: people love getting comped. No matter how cheap or silly, if it came for free people will remember you fondly for it and give you their business in the future. And they will probably blog and post on HN about it too :)

If I ever open a restaurant I am going to randomly dispense free appetizers and desserts. If I ever run a (freemium) startup, I am going to randomly give away free accounts. Not to everyone, not so much that it hurts the bottom line, but enough that the buzz and goodwill generated outweighs whatever loss I'm taking.