I've had a little back-burner project going for some time now: a list of open-source and/or freeware tools that knowledge workers can use in lieu of commercial software, along with reviews and tips for their use.
Sometimes the substitutions are dead simple: OpenOffice.org is a great substitute for Microsoft Office 2003, and is even 99% file-compatible with your Office (Word, Excel, Powerpoint) documents.
Often there are packages that can be cobbled together to produce equivalent results... I haven't (yet) found an XML publishing tool with an interface as nice as Adobe Framemaker, but there are an embarrassing array of choices of XML editors, style tools, and the like.
But I've just found a new tool for my toolbox, and wanted to tell you about it: I think I've found an open-source replacement for Visio.
Dia, a drawing program, is designed from the ground up to be a template-based drawing tool, like the commercial package Visio. In some ways, it looks to be nicer than Visio, especially if you do any work with UML.
As a technical writer and trainer, it seems like I pretty much *live* in Visio, churning out flowcharts, network diagrams, and the like. I'm going to give Dia a spin and see how it goes.
UPDATE: Preliminary version of toolbox document here.