It's good to know that I'm not the only one with this obsession. As everyone else, I must contribute a few that you left out.
First is Tag, a simple (and very young) text editor made for XHTML editing. It lacks a lot of powerful features but concentrates pretty hard on the right ones. The implementation of it's live preview is phenomenal. I don't personally use it daily, but it's worth a look.
Now, Ulysses. Ulysses is more than a plain text editor, but it's focus is on the editing of plain text. It's made as a text editor for creative writers that aims to simplify the task of creative writing. It's tag line is: Where Word and Style are not defined thru buttons and palettes. It's worth checking out.
I love SkEdit, but it keeps crashing… maybe when I switch to Tiger and wipe my HD…
( written in SubEthaEdit )