in R, you're fooling yourself if you're not using ggplot -- all hail Hadley Wickham, our benevolent overlord! In Python, I haven't yet settled on a favorite tool. Recently I used matplotlib but it's a little clunky/verbose, so happy to hear others' recommendations.

For anything Java, Spock for tests and GPars for concurrency. Both originate from the Groovy ecosystem, are super-easy to use and fit projects of any size. Must-haves in any Java-Toolbelt.

Here is a good post on chart.js