TiddlyWiki - a non-linear personal web notebook
Scrapbox - A new style of note-taking that lets you create, discuss, and learn together in one self-organizing space.
Personaldb - Note taking with non-linear power
Unit Notes for iOS - A simple and powerful note-taking app.
Roam Research - A note-taking tool for networked thought
Doceri - Doceri is a scalable suite of products that allows a teacher or presenter to control a computer's desktop, to control audiovisual technology, and to annotate any presentation in real time with the Apple™ iPad™.