MultiMarkdown Composer 2.1 beta (build 2) — This is a preview release of 2.1. It is non-sandboxed, and requires that you have a purchased copy of version 2 on your machine (at least for the first time you run a non-sandboxed build). Please be sure to run the Mac App Store copy of version 2.0 at least once before running this copy. For more information, see the knowledge base article.
MultiMarkdown Composer - for Owners of Version 1
MultiMarkdown Composer 2.0 (build 2) — This is the non-sandboxed version of MultiMarkdown Composer. You must have a working version of the App Store version for this to run. The 2.0 version of Composer will also respect the App Store license from Composer version 1.1.2. This means that you get free use of version 2.0 if you have purchased Composer version 1 from the Mac App Store. Future updates will require the purchase of Composer 2 from the Mac App Store. More information is here. (Updated 1/16/13)
MultiMarkdown QuickLook Generator — A free program from Fletcher T. Penney to preview MultiMarkdown text or OPML documents as rendered web pages. An alternate version of this program is available on github, but this version is more reliable. It uses proprietary code, so the source code is not available. More information is here. (Updated 1/7/13)
mmdc - for Composer version 2 — A command line utility that allows you to type mmdc or mmdc foo.txt to edit or create files with Composer from Terminal. (Updated 2013–01–24)