Chyrp is a blogging engine designed to be very lightweight while retaining functionality. It has powerful theme and extension engines, so you can personalize it however you want. The code is well-documented, and it has a very strong structure that's loosely based on the MVC design pattern. Chyrp allows importation from several different blogging engines and uses a system called "feathers", which are basically templates for custom posts.
Html Writr is an innovative system that allows users with little to no technical knowledge to edit static HTML files. It is very easy to setup, and requires no database to use. The editing experience is simplistic but full featured, using nicedit for the WYSIWYG editor, and allowing users to edit the page title, meta description, and meta keywords. Preparing HTML files for the HTML writer to edit is very quick; just a couple of lines of code and you're done.