bitbucket is a hosting site for the distributed version control systems (DVCS) Git and Mercurial. The service offering includes an issue tracker and wiki, as well as integration with a number of popular services such as Basecamp, Flowdock and Twitter.
This is the website for the Pro Git book, written by Scott Chacon and published by Apress. Here you can find the full content of the book, a blog with tips and updates about Git and the book and open source projects related to Git or referenced in the book.