When I write in my WP I sometimes used Password protected entries, But I dont' want to see them on the main blog page. I'd love it if I could post in a category and when I went to my index.php that certain category just wasn't there. But you obviously could still see it on it's own Category page.
Also, sometimes I like to make just a small part of an entry password protected.
If these are around and I just haven't found them, Sorry. But it'd be really helpful to have something like this.