Trello preview for markdown outcome

I've hunted around the interwebs for just this solution, and HIGHLY recommend using Markdown Here. It is a browser extension for Chrome, Firefox and Safari that lets one toggle back-and-forth between Markdown and HTML. It's original use-case is for in composing e-mail, but it "works great" in Google Sites. Also, it supports TeX math formula, which for researchers, I would imagine could be quite useful.

FWIW, I started down the path of using the Markdown Site Editor suggested by @dnozay, but it seemed overly complicated for a few reasons:

• It forces each site maintainer to add it for Markdown functionality.
• It has the potential to break as Google's tools change, and someone then has to get the latest version (possibly for each site).
• Some environments have scripting and/or google app engine hobbled for security/policy/etc. reasons
• Philosophically, it makes Google Sites try to be something it's not.

Using Markdown Here means

• No additional code needs to be added to each google site.
• It is a well maintained tool that is installed once in a browser and useful is in many places (e-mail, sites, blogger, facebook, tumblr, tinymce, etc.)
• The onus of responsibility is on the individual who wants to use Markdown (and TeX).
• It let's Sites be Sites, and Markdown writers be Markdown writers.

Use ~~double tildes around the words~~.