http://progit.org/ is a website for the Pro Git book, written by Scott Chacon. Whats great is that you can read the full contents online (like the SVN book) so it acts as a great Git resource to have. Covering everything from a history of Git, to getting started, the Protocols, distributed workflows, and event migrating from SVN to Git. If you haven't looked at Git yet or just starting then bookmark it now.
You can of course support the book and buy a print copy copy for your bookshelf.