Here, in no particular order, are the tools we use.
Middleman is a Ruby tool that builds and generates our website code. It let's us use a variety of tools and languages (Slim, Sass, Compass, YAML, localization, etc.) in development and then automates the construction of our static pages. It has become indispensable.
Slim is a lightweight templating engine for Ruby. It reduces the amount of syntax to the most basic parts while still being readable. Mostly used to generate HTML it can also process a variety of syntaxes.
Markdown is a text-to-HTML conversion tool. We use it to write nearly all the content for our site.
Short for Simply Awesome Style Sheets, SASS (and it's sister, SCSS), greatly speed up the authoring of CSS. Adding variables, equations and other functionality to CSS, SASS is one of the most powerful tools in our arsenal. If you haven't tried it yet we recommend this article on A List Apart: Getting Started with SASS.
Compass is an open-source CSS framework. It contains a large library of mixins for use with SASS or SCSS that greatly speed up our SASS development.
Foundation is our framework of choice for building web sites.
We use this in conjunction with selectivizr to enable :before and :after pseudo-selectors as well as the content: attribute.
We would like to extend a hearty thank you to these people. Each of them have contributed greatly to our success.
Hasan Alayli, Marko Bijelic, Chris Bonham, J. Bryan Graves, Stan Burnitt, Olivier Constant, Marinus Damm, Gary Ellingson, Sam Gendler, Hans Gutren, Tania Hayward, Daniel Holmlund, Britt Ihrig, Laurent Istria, Michael Jinks, Chris Lee, Beth Levine, JD Mooney, Scott Nichols, Alex Novikov, Scott Olson, Jay Palat, Adrian Robert, Ed Sarausad, Austin Schutz, Dan Short, Alok Singh, Barney Stein, Allison Taylor, Raghav Vadali, Eric Welton, Alex Wenckus, Gil Winkelman, Mike Zuhl