For example, I really wish I could show my location to friends-of-friends and my birthday to only friends.
And speaking of friends-of-friends based security, I wish LiveJournal offered such a privacy setting for journal posts. Would that be difficult to implement?
Oh, last, but not least, since the community's profile asked for it, a quick introduction: Let's see, umm... I think I'll let my journal mostly speak for itself. It has lots of pictures for you people who don't like to read too. ;-P