Dateutils are a bunch of tools that revolve around fiddling with dates and times in the command line, with a strong focus on use cases that arise when dealing with large amounts of financial data. Their target market is shell scripts that need date calculations or calendar conversions, and as such they are highly pipe-able and modeled after their well-known cousins (e.g. dtest vs. test, or dgrep vs. grep).
jQuery Calx is powerful yet easy to use jQuery plugin for building calculation forms or calculation tables. It parses provided formulae and performs calculations, scans for form changes and updates results automatically, and formats plain numbers into currency format, ordinal numbers, etc. It is suitable for both simple ($A+$B) formulae and complex ones such as ($I*$P*((1 + $I)^$N)) / (1 - ((1 + $I)^$N)).