The latest release as of today is FreeMind 0.9.0 from February 19, 2011.
See http://freemind.sourceforge.net/wiki/index.php/Download or http://sourceforge.net/projects/freemind/
Amazing software guys! I even wrote reveiw (http://www.goldsoftware.ru/freemind) on Russian for FreeMind. Just one note. I noticed some lags on Linux system. (celeron 2.8ghz, 1gb ram)
Great Mind Mapping Tool
This program does wonders. A lot of the commercial mind mapping only has marginal improvements over this one.
There is definitely room for improvement, but due to the nature of open-source, i guess the power is in your hands too.
Nice that the saved files are XML. I can see some funky XSLT to transform this between other Open Source projects being possible.
An open, cross-platform journaling program.
A scientific plotting package.