The Wayback Machine - https://web.archive.org/web/20151225052512/http://git-scm.com/docs
Git --distributed-is-the-new-centralized

Reference

Quick reference guides: GitHub Cheat Sheet (PDF)  |  Visual Git Cheat Sheet (SVG | PNG)

Setup and Config

Getting and Creating Projects

Basic Snapshotting

Branching and Merging

Inspection and Comparison

Patching

Debugging

External Systems

Administration

Server Admin

Plumbing Commands