I'm an ecologist and spend most of my time on data analysis and developing simulation models.
Main languages: Java, C, R (http://cran.r-project.org/) and ones that I invent with ANTLR
I contribute to:
JAI-tools http://http://code.google.com/p/jai-tools
Jiffle http://code.google.com/p/jiffle
GeoTools http://geotools.codehaus.org/
less...