I think the second restriction is too much. As a middle ground, I would go with ecto or MarsEdit so you have a desktop client. Ecto can even use TextMate for editing. If you go this route, I would recommend Movable Type or Wordpress as they have really good support for XML-RPC amd some other platforms are seriously lacking in that area. Most webhosts (Dreamhost and Bluehost for sure) have one-click installs of Wordpress to help with the hassle bit.

Hope this helps,

You might like Lame Blog. I haven't used it, so I can't say how it is. I don't like the compile-and-upload model because you have to rely on third party providers for comments and so forth.

If you relax the second restriction, but still want to blog with a text editor and plain text, you might like PyBlosxom or another Blosxom derivative.

I've used both Movable Type and WordPress pretty extensively, and while you couldn't go wrong with either one, I highly recommend WordPress for it's ease of use and flexibility. And like Berko said, you can use a blogging client like Mars Edit to manage it locally.

If you really didn't want to install software on a server, doesn't the iWeb + .Mac combo generate blogs?

I haven't worked with it much yet, but I saw this screencast of Flock and I was pretty impressed with what it had to offer. You might check it out.

ok, i installed wordpress, and it seems to be working well. i guess i was used to the compile-on-my-machine version of blogging software and I needed to get with the times. Thanks, folks.

There's a big list of Wordpress-compatible clients at http://codex.wordpress.org/Weblog_Client -- I've not tried anything but Vagablog for PalmOS. Typically, I'll still compose my posts directly inside Wordpress' included editor.