If there's ever a quintessential application to build when you first dive into a framework, it's the blog. That's what I did with Snook.ca when I first got into CakePHP.
Then for a recent client project, also built using CakePHP, I was asked to integrate a blog. I took this opportunity to take a chunk of the code I used to build my own site and break it out into its own blog plugin: Snogs.
Snogs is Snook's Blogs and is a simple multi-blog engine for CakePHP. It's hosted over at CakeForge where you can download the application, access the Subversion repository or supply feedback.
I'm releasing this as open source. If you're interested in joining the project and enhancing Snogs then by all means let me know. Also of note, I've included the spam component I talked about previously.
While my own site doesn't run off of it, it will. I'm intending to rebuild much of Snook.ca using Snogs to see how well everything integrates and it will no doubt inspire me to add some features I find useful.
(And let me know if you're getting tired of all these Sn- prefixed projects. I think it's fun but there's always too much of a good thing.)