GitHub Salesforce Deploy Tool
Read more about this tool at my blog post here.
Update: 3 April 2016: Maintainance to move to Cedar-14 on Heroku, enhancements, bug fixes and a UI restlye, see blog for more details.
Update: 21 May 2015: Added support for private GitHub repositories. When deploying a private repository the user is redirected to GitHub authorization window. After authorizing, a private repository can be deployed exactly the same way as a public one. Contributed by Moti Korets.
Update: 27th September 2014: Added feature to generate Deploy to Salesforce button, thanks to Karanraj for the image.
Updated: 7th December 2013: Added Sandbox support see here