Notational Velocity Alt
nvALT is a fork of the original Notational Velocity with some additional features and some interface modifications. It is a work in progress.
This fork by Brett Terpstra comes with widescreen layout, a shortcut to collapse the notes panel, Markdown, Textile and MultiMarkdown support, HTML source code tab in the Preview window. It’s really a highly customized version of the original NV, possibly inspired by Elastic Threads’ mod. The Preview window is amazingly useful.