VoodooPad

From Flying Meat's website...

VoodooPad is a garden for your thoughts. Plant ideas, images, lists and anything else you need to keep track of. VoodooPad grows with you, without getting in the way — no fences to box you in! Type in notes, highlight important words or phrases and create new pages. Drag and drop folders, images, applications, or URLs into VoodooPad — they're linked up just like on the web. With powerful search, nothing will be lost or out of reach.

The more you put into it, the better it gets.

http://www.flyingmeat.com/voodoopad/

Source: http://trac.wikidpad2.webfactional.com/wiki/VoodooPad