Mark Headd documents some great experiments in procurement going on at the City of Philadelphia, using Github to solicit proposals – 

In addition, several of the responses were highly creative – responding firms took advantage of the fact that the submission platform was a GitHub repo and made the most of the opportunity. One firm created a compelling webpage using GitHub pages to tell the story of Philadelphia residents who might use the new mobile app – they didn’t do this in addition to their standard response, this was their response.