Computer Technology

Networking

• Look@LAN Network Monitor - "World's Faster Network Monitoring software", it allows you to monitor your LAN or your network.
• WOS - (Webserver on a Stick) a complete Apache webserver that can run from a USB stick (or hard disk). Contains preinstalled software packages, including PHP and mySQL

Simulators

Web Design

• OSWD - Open Source Web Design - free templates for web pages

Computer Studies

Editors

• Alice - An innovative 3D programming environment that makes it easy to create an animation for telling a story, playing an interactive game, or a video to share on the web.
• Build Your Own Blocks - An extension of Scratch that allows users to create procedures, create multi-dimensional lists, perform recursive calls, and much more while still using a drag-and-drop visual IDE.
• Eclipse IDE - A popular, open source (free) IDE. See wikipedia for further details.
• DRJava - Java IDE that allows lines of Java to be run interactively
• GameMaker - "Start building your own great games in no time"
• BlueJ - Java IDE that shows a project as a UML class diagram
• Netbeans for BlueJ - The collaboration of the NetBeans and BlueJ teams has resulted in the development of a new version of NetBeans: NetBeans IDE BlueJ Edition
• Processing - Processing is an open source programming language and environment for people who want to create images, animations, and interactions. Also a great language for Arduino programming! 
• Scratch - Create and share your own interactive stories, games, music, and art.