Brett Terpstra
nvALT
FreeNotational Velocity fork with MultiMarkdown support.
Mac
PopMaker
FreeOS X app for generating PopClip extensions.
Mac
Titler
FreeAn OS X System Service to add titles and affiliate tokens to URLs (Markdown format) in selected text.
Mac
Markdown Service Tools
FreeOS X Services for creating Markdown-formatted text.
Mac
Marked
Trial versionPreviewer MultiMarkdown, Markdown, text and HTML files.
Mac