Code Igniter
I'm absolutely in love. While I bored was at JAX, I searched around for a PHP framework like Ruby on Rails. I already knew about CakePHP, but I wasn't convinced. I looked at a few others, but nothing caught my eye. Then I discovered Code Igniter.
Code Igniter comes from the people who make Expression Engine. I had already heard great things about that, and I had even considered purchasing a license. Code Igniter, however, is free and open source. It's quite new (first beta was released in February) but it is incredibly professional and already very stable.
Code Igniter does absolutely everything I want it to, and nothing I don't want it to. It's incredibly simple and clean, so there are no surprises or weird tricks. It forces you to organize your code using an MVC structure (actually, a VC structure — using a model is optional). This keeps your code cleaner and easier to maintain. It also comes with a number of libraries that help with common web development things like email and uploaded files.
This weekend, I rewrote my whole custom-made blog code for this site. It only took about 4 or 5 hours, and it was actually fun to do. It also reduced the amount of code I had, and makes it much, much easier to maintain and change in the future. For example, until now I was too lazy to add contact pages properly, so I just added blog articles for Contact Me, etc. and pointed links at these. Now, I've changed the pages to use /contact/me and /contact/hire, and I could easily reuse my blog template. This change took about 10 minutes.
By default, URLs are of the form /class/function/parameters. But if you want to do something different (I use /blog/2006/5/article-name), you can set up routing rules for anything you want. Actually, Code Igniter is totally flexible to let you do whatever you want. Anytime I got stuck, I poked around in the documentation and found that there was something in place specifically for my problem.
Also wonderful: only the minimal amount of PHP is loaded to create each page. You can load classes globally, if you need them, but by default, you only load what you need when you need it. This keeps every page as fast as possible, something I was worried about with other frameworks like CakePHP.
Okay, that's enough ranting. If you use PHP, check out Code Igniter. There are some videos you can watch to see just how easy Code Igniter really is. The user guide is also a pleasant read and explains everything really well.