I friend myself as myself (at least I think I have in this journal, I definitely have in my RL one) because I've got my bookmarks on the friends page and everything is all right there. Also, I like looking at my icon when I re-read my own entries. I've got a journal on GJ for a Roleplaying site and you need the icons to even tell who's writing the post (well, you can usually tell, but it's first person and easier to tell with the icon).

I would friend myself as somebody else because I don't write much and when I do, I'm usually announcing a story update (or answering a quiz, and those are fun, too).