TiddlyWiki - a non-linear personal web notebook
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Personaldb - Note taking with non-linear power
Draw.Chat - Anonymous real-time whiteboard with text and video chat.
Roam Research - A note-taking tool for networked thought
Scrapbox - A new style of note-taking that lets you create, discuss, and learn together in one self-organizing space.