Apart from just programming humble calculators, I have also programmed quite a bit on the computer. Although I haven't written anything groundbreaking, these are a couple programs of note.

Name Description
CZ80 Compiler My own Z80 compiler based on Assembly Studio 8x. Has cool features such as local labels and proper case-insensitive labels, and because it's a DOS program it lets you use your favorite editor.
Code Converter v.5 A perl program that makes it easy to convert the style of indentation, operand alignment, and labels in Z80 source files.
Latex-To-HTML Converter A Perl script which parses latex source and converts it into lovely HTML. It also uses the syntax highlighter listed below to highlight any code examples in lovely colors. This program is currently being used to publish three versions of "How To Think Like a Computer Scientist" on the Open Book Project, and can be optimized for other needs as well.
Syntax Highlighter A nifty HTML syntax-highlighter that uses external files to determine the specifications for the language being used. Perl source code is included (duh), as well as four example languages: C++, Java, Perl, and Python.
Pclasses An LGPL'ed, reverse-engineered implementation of the College Boards's C++ AP classes. Written for the Open Book Project at my high school.

And of course, what's a computer geek without a screenshot of their desktop? :-)