It's interesting to me how that my 20th birthday interests me more than my 18th did or my 21st will. When I turn 21, I'll gain the permission to drink and gamble, two things I don't really intend to do. When I turned 18, I gained the permission to smoke and play the lottery, which are both irrelevant, enter into contracts and have my own bank account, both of which are useful but I couldn't use for a while anyway, and look at porn, which I'd never really been stopped by before.
But turning 20... it's got none of that, but what it has is a change of leading digit. For some reason, that has my attention. *shrug*
Not that I'm going to do anything for my 20th birthday; I've got work to do, and I'll be tired in the evening, and my entire product team is going to be out of the office for the day.