My hobby-horse is the second law of thermodynamics. Therefore, I am permanently looking for possible applications outside physics. In this article, I cover the Lorenz curve and the Pareto rule from economical sciences. I believe I have found a plausible explication following the statistical methods of Ludwig Boltzmann.
You want to find out whether your terminal supports 256 colors? No problem, there's a small application in the XTerm package named "256colors.pl". But, uugh, it's written in Perl. I wrote my own in Ruby. I just wanted to show how nice things can be done in Ruby. If you want to know whether your terminal handles 256 colors, run it. Maybe you like to compare the Perl code of the original XTerm package and the Ruby program; maybe you'll find yourself confused by both of them.
You are editing in Vim and programming in Ruby? Now, here's the ultimate Ruby expression evaluator. Mark the section you want to pass through the Ruby interpreter or give a range. Type the command "Ruby". There also is a command "RubySum" for adding lines of numbers or even expressions. The command "RubySums" appends to each line the sum so far. I use it every day; another great point for Vim users.