I tend to go through my friends' list every year or so and clear out a lot of people. I like to keep my account to as small a number as possible... so if after a year I realize that 1) I don't really communicate with the person 2) I don't particularly care for reading their posts and 3) they never comment on mine (thus would assume they don't particularly care) I'll then delete them.

Sometimes they readd me. Embarassing as I feel horrible, but I'll usually post up that I must have accidentally deleted them during my cull (which, has actually happened!). I'll keep them on after then because they obviously do pay attention to whatever I'm up to.

Then again - I'm fairly particular with who I add. They are people whom I either know I really WANT to keep up with.... or people who I see a lot and feel guilty if I didn't accept them.

It's really just up to me to be responsible for my experience on facebook.