This article from Fast Company promotes sending a personal, thoughtful, and lengthy email out to your most valued people in your network about 4 times a year in order to maintain a strong networking relationship (this is in addition to more personal, face-to-face time). As Jason Shen says in the article, "building a strong network is one thing, and keeping it strong is another."
I have a longing for connections, or networks, to feel more meaningful and valued, rather than transactional and need-based. Perhaps this is a step in that direction.
For reference and further reading: