Meh, it really depends on your circle of friends and what you do for hobbies. A year or two ago I was up to 500-600 friends on Facebook, and they were all people that I legitimately knew and would say hi to if we crossed paths walking down the street. Maybe not true "friends", but they weren't just randoms. When I was guiding ski trips, I was meeting a couple hundred new people a year, and naturally being the awesome guy that I was, they'd often look me up on Facebook and add me after the trip. In fact a lot of customers from those days remain friends that I occasionally hang out with.
That being said, I did go through my entire friend's list and removed over half of them, with the rough guideline being that if I hadn't personally interacted with them in the past year or two, that they were given the boot. That left me with about 220.
