Here are some programs I've written that I found useful. Most are command line programs available from the programming section, that I've addex xmlrpc functionality to, and AJAXified. AJAX is currently disabled because the jsolait library seems to be breaking IE.

Programmer's Calculator

A calculator that evaluates simple expressions and gives the result in decimal, hex, octal and binary.

Nokia Predictive Text Simulator

For simulating the results of typing SMS messages using predictive text, when not paying attention