Keeping in Touch

What's the best way to keep in touch and how do you decide who to keep in touch with?
We have 100s of friends on facebook, follow people on twitter and even have 100+ numbers in our mobile phone memories. But even so I find myself interacting with the same group of people all of whom I was in regular contact with before social networking took over my life. There may be the odd flurry of tweets or wall posts when someone "new" is discovered (and by new I mean from infants school) but generally after a while you settle in to seeing the odd status update and that's it. Not even that in some cases if they don't post their status (or they post their status too much so you hide them from your feed).
Then there are people you meet in person. You might give them your number and they give you their number, but you can't quite work out when/why either of you would ever call. Yes you can have my number but we know we won't be speaking till the next time we happen to be in the same place. However human interaction beats internet interaction (she says as she is typing a blog on a train avoiding eye contact with the people around me) we have after all be interacting one to one in person for thousands of years.
So I've decided to make the effort. The next time I see someone and we swap numbers I am going to text them or the next time someone adds me on FB I will send them a message. Maybe it will lead to a new member of my small group or maybe they will ignore me, but at least I'll know I've made the effort.