The one thing I like about Facebook: birthday reminders. I’m not super about remembering people’s birthdays (I used to be wizard, but that time is long gone), and the weekly reminder of who’s birthday is coming is really nice. Alternately, it’s nice to get little “happy birthday” notes from a weird cross-section of people in one’s life: friends from junior high, high school, and college, including my long-time boyfriend from back in the day; the DM from my weekly D&D game; neighborhood association people; other local friends & acquaintances; and people I know from the internet. Also, my 10th grade biology teacher.
I’ve heard the complaint that Facebook birthday messages are shallow/meaningless, but I don’t find that to be so. For me, it’s just a tiny loose connection that reminds me of a web of people who I may not talk to all the time, but who saw my name and thought well enough to say hi.
(FWIW, I like this feature on the genealogy site Geni, too. It’s how I know my cousins’ birthdays, and that one of them has a wedding anniversary on my birthday.)