A Zenbe user blogged about how free customers aren’t necessarily the best customers when it comes to asking them to pay…

http://entresting.com/contracts-and-compliments

…but that doesn’t mean that free customers don’t add value. We learned a lot running a free service that 100,000 people or more signed up for. That expertise went into engineering a much better not-free service. While I am not sure the benefits justify all the expense of our free service right now, there are definitely benefits. So its not all that bad…
PS: don’t forget about this stuff..
http://www.zenbe.com/welcome/goodies