The particular software I'm using for creating the content on this website is Movable Type . There are other blogging packages out there, but this one suited my needs pretty well. If you're not planning to host your own site, there are a few more choices out there, but MovableType let me handle everything locally, and works just fine on the Mac.
The folks over at MacZealots have a nice tutorial on getting Movable installed under Panther (Mac OS X 10.3). If you decide to follow their steps, be advised that the version of MySQL they're linking to is out of date, go here for the latest production release. It's probably best to avoid alpha and development releases unless you know what you're doing.
Be sure to read through the comments on the MacZealots page for info that others have written in regarding the procedures listed, some folks had issues and some good fixes are listed. In particular, I didn't care for my past entried to be in a directory called 'Archives', especially since even the most recent entry is stored in that directory, which becomes part of the URL if someone pulls up that entry directly. Instead, I called that folder 'Articles'. If you decide to go with a different name, be sure to change any other references to 'Archives' when you set this up.
The main Movable site has a running list of sites running this software that were recently updates, check through those for some ideas on what you can do with the software, there are some creative folks out there. You don't need to be a master web designer to get something decent up and running, and there's always time to play with the settings once you've got a site online.