Blosxom is a lightweight yet feature-packed weblog application designed from the ground up with simplicity, usability, and interoperability in mind.
Easy to tinker with.
I am returning to Blosxom after several years with WordPress and am delighted to do so. As a commenter below said, it is simple and functional and, compared to WP, monstrously fast. As an old-school HTML coder I couldn't ask for more.
Simple and functional, a jewel amongst popular blog engines these days.