Pangea is a project mainly written in PHP, it's free.
Base theme to rule them all
Minimalistic and modular HTML5 base theme tailored for Drupal distributions
Credits:
Modularity and Drupal distro-tailoring best-practices from OpenPublish (http://openpublishapp.com) and OpenPublic (htt://openpublicapp.com)
HTML5 best-practices adopted from the HTML5 Boilerplate project (https://github.com/paulirish/html5-boilerplate)