So, my husband and I are on Facebook.
I've been playing around with it, finally figured out how to add my blog feed to my profile. I don't really love the Events calendar though. There's no way to add a generic event (like a birthday or anniversary) without providing a lot of extra information. At least, if there is, I haven't figured it out yet.
With all the apps one can install, a profile can become cluttered fairly quickly. It would be nice if there were more ways of organizing information. I'd also love it if the profile and home page were skinnable.
Facebook is the ultimate online referral service (I know a friend of a friend who knows... etc). The more people you know, or who know you, the more likely you are to be a real person, the more people who don't know you or have never met you can trust you. In fact, Facebook seems to be making a concerted effort to address the issues of trust online.
Recall my annoyance with a certain article printed in the Christian Renewal some time ago. Having played around with Facebook, I can confidently say that nearly everything in that article was wrong.
If I were still in school, Facebook would make a great topic for a research paper.