Software
Apps or extensions/modifications to other apps
Phiddle [open source]: Screen pixel measuring app for desktop computers.
SpamDetector [open source]: A PiranhaCMS module for spam detection. Simple module for Piranha CMS.
WLMerge [open source]: Windows Desktop program to merge Bricklink Wanted Lists.
Projects
Projects covering more than just an app or extension
SUL: A cockpit simulator for a Swedish Military Jet, including full cockpit with software integration.
MOCs: I build and create stuff in Lego and here are some MOC-related things I want to share (what is a MOC?).