For what it's worth... I keep a project called "Keeping in Touch" with contexts of usually Phone or Email. Under that are tasks for individuals I want to keep in contact with (both personal and professional).
Keep in touch with Bob Smith. (Repeats every 5 weeks from completion date, start and due dates one week apart) @Email.
This just reminds me that I should shoot Bob and email about every 5 weeks to touch base and keep current. If an action comes out of that (like getting together for dinner/drinks), then it goes right back in to OF.
It's not perfect, but it works for me.