In the old days people wrote diaries. That way they could choose whom to share their story with, they could burn them or they could hand them to their spawns.
I don't see how that is any different with the privacy settings in Facebook.
And I think it's superior to a diary in that it's not only recording my thoughts on something, but also the minutiae of my day to day, whom I've associated with and my interactions with them, etc.
I'm a little surprised at the responses my original post received actually. Am I the only one that uses Facebook for this purpose?