My favorite development environment
I thought I'd add some words about the development environment that I feel most comfortable with.
First, I use AGX for most of my plone development. It's useful as a quick skeleton generator, but also as a way to structure the content. To generate the UML files I use Poseidon Community Edition. Up until recently it was buggy, and I still consider it to be, but I learned what to do so I won't trigger the bugs (quick tip: don't ever rename tagged values, delete it and recreate it. If you rename a tgv, it will rename that tgv in the entire model). I've tried ArgoUML and, despite having better support for AGX, it felt buggy. And I don't like the way you have to hunt down the tgvs in that long list when adding one.
I use JEdit as text editor. It's not the greatest python editor, but it's a good all-arounder. I like its xml support, it's great when editing page templates. It's fast, has a ton of plugins and a nice "hypersearch" bar that you can place at the top and use it to quickly search in the curent document. Lately I've started using SPE for a wxpython based project, and I'm also trying Eclipse with pydev.
When creating a plone skin, the Firefox Dom Inspector is invaluable.
I use Ubuntu Dapper as the main OS. Although I have dual boot, 99% of the time I spend it in Linux. It has been my main OS since Breezy Badger came out, and I like it a lot. It runs Java software really fast and Gnome is terific DE. I was a KDE (with WindowsMaker as window manager) fan until my first contact with Ubuntu. It's nice! I bind alt + 1, 2 and so on to the each desktop and so I can switch really fast to the application I'm interested in. I put Jedit on desktop 1, the gnome terminal on desktop 2 and firefox on desktop 3. I can run Internet Explorer 6 and Photoshop 7, to cover even the last Windows needs.
And last, I listen to Radio Paradise with Rhythmbox. When I feel like exploring, I use StreamTuner or head over to Radio Grassy Hill, BorderRadio or Deviant Audio. Either that, or listen to my extensive collection of Grateful Dead mp3 recordings.