GlassCalc
A lightweight yet extensive and flexible calculator for Windows. It lets you enter equations as text, supports user-defined functions and variables, and saves the full history of your calculations.
MD5
A simple command line application that calculates the MD5 hash of a file. It can also take another MD5 hash and check whether they match.
Userscripts
A list of userscripts I've written. They make your web browser do cool things it didn't do before.