UCLA Statistics has a pretty extensive list of resources on how to use R and GRASS. For those unfamiliar, R is a programming language and environment for statistical computing and graphics. GRASS is an open source geographic information system (GIS). And of course, both are completely free and completely useful.
Useful Stat Resources for R and GRASS
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Who is Older and Younger than You
Here’s a chart to show you how long you have until you start to feel your age.