I often equate good link building with relationship building. Since a link basically serves as an online recommendation of services, site owners have to be willing to stake their own reputation on what their users will find after the click. That's why good link building goes beyond simply putting together great content or a great product. It focuses on securing a relationship between two individuals so that the link follows naturally.
That's why I think it's important to sometimes share examples of what good relationship building looks like.
A few weeks ago, I received an email from a reader of my pet project site, The Lactivist. The reader wrote to compliment me on a particular blog post and made mention of her own experience on the subject. I responded with some additional thoughts of my own. She responded back and made mention of a product that she sells that addresses the issue we were discussing. She offered to send me one of the products if I would be interested in reviewing it.