PrivateJournal
I use a LiveJournal account as a private journal, and so all my posts are private. As far as I’ve been able to tell so far, LiveJournal always defaults to public when posting a new entry.
After getting a bit annoyed, I realised GreaseMonkey would be the perfect tool to fix the UI for myself. So, I wrote a quick script to set the privacy selector to “Private” on the post page. And so, I present possibly the shortest GreaseMonkey script ever. Enjoy!