Blosxom (pronounced "blossom") is Rael Dornfest's tiny (60-line) implementation of a Blogger-style weblog engine.
"Tiny" software -- programs that try to capture the essence of a big system in a very small space -- were a fascinating feature of the early personal computing landscape. This is the first time I remember seeing a stunt like this in a long time; it's like running into an old friend.
MacOS X comes with a full-scale Apache installation for its personal Web sharing system. That's nifty, because you can install cgi systems like Bloxsom locally and play with them safely, without fear of doing Something Bad to your public sites and with all the speed and convenience of local debugging.