The Command Line
Free - GPL v2
Free to use. Source not available. Sourcetree is a full featured and free Git UI for both Mac and Windows that provides an interface for pretty much everything you can do in the...
Magit is an interface to the version control system Git, implemented as an Emacs package. Magit aspires to be a complete Git porcelain.
$79/user. Free for non-commercial use.
Free - GPL v2 or later. Text-mode Git repo viewer.
fugitive (via vim)
Free - VIM license
Free - MIT license
vimagit (via vim)
Get the the best of magit interactive workflow within vim.
Proprietary license, source not available
SublimeGit (via Sublime Text)