Torchpad - Wiki farm with markdown based wikis.
TiddlyWiki - a non-linear personal web notebook
Referata - Referata offers hosting of semantic wikis, allowing you to add, structure and store data so it can...
Zim Wiki - Zim is a graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images.
ZuluPad - ZuluPad is a notepad on crack.
ConnectedText - ConnectedText is a powerful but simple information management system.