After almost a year of pretty much exclusively using open source tools at home, here's my list of indispensable tools:
Gantt Project. This is a great java-based project management tool. Because it's java, it works in windows, linux, and one would presume, osx.
Open Office. What better enabler is there than a free, robust office suite. It's bloated, a bit buggy and slow, but frees you from the shackles of needing Microsoft Office.
FreeMind. This is a very robust and reliable java-based "mind-mapping" tool. I can't really describe it except to say that it's great for brainstorming in a non-linear fashion. I use it for goal setting and idea generation.
The GIMP. Want 60% of the functionality of Photoshop at 0% of the price? The GIMP is easy to use, flexible, and a powerful image editor.
Nvu is a descent wysiwyg html editor that handles divs and layers very well.
Firefox. 'Nuff said.
Amarok. Best player there is. Handles your collection, downloads the artwork, builds dynamic playlists, has ipod connectivity, talks to last.fm to get suggested tracks -- I don't even use playlists anymore, I queue up a few tracks that I'm in the mood in and I let Amarok/last.fm suggest the rest.
