There are some people whom I haven't seen for years, but I keep them on the FOJ list and calling them on their birthdays.
Admittedly, it is awkward sometimes, but to me there is an inherent Value of Networking (see also: Networking for Knowledge).
I called Ursula (whom I met 4 years ago and haven't seen since) on her bday and she was admittedly, a bit taken aback, thinking it odd.
Well, 5 months later, she pinged me and asked for a recommendation for a Financial Advisor.
I gave her one. She hired him.
That's why I do it.