I am posting this with a Dashboard widget.

There's this Dashboard widget that you can use to post to a LiveJournal. There isn't any auto-fill on the obvious things, and I haven't found any way to make the text anything other than tiny. I could see doing this with a widget, but this one's not quite there yet.

Anyway, I came to like some of these widgets pretty quickly. I think my favorites are the Yellow Pages and weather dealies, and the Wikipedia one you can download.