useful command line application called Terminal Velocity. It is a fast, cross-platform, CLI note-taking application.
Plain-text file notepad with markdown support and ownCloud integration
Epistle is a simple and clean text editor that can sync all your notes with Dropbox. It also supports the Markdown language, with a live preview of your notes.
Simplenote syncing note-taking application, inspired by Notational Velocity and ResophNotes, but uglier and cross-platformerer.
A fork of Notational Velocity with MultiMarkdown preview and advanced Markdown editing capabilities.
venn, coffee and notes-circles
Memonic is a personal organizer to save and use just about any information worth keeping. It's a bit like a brain extension for notes, memos, thoughts, clips and much much more.
Must have hack by Steven Frank.
NOTATIONAL VELOCITY is an application that stores and retrieves notes.