Meld is a visual diff and merge tool. It integrates with most version control systems. The diff viewer lets you edit files in place (diffs update dynamically), and a middle column shows detailed changes and allows merges. The margins show location of changes for easy browsing, and it also features a tabbed interface that allows you to open many diffs at once.
git-info-bar is a ksh, bash, gitbash, and Git shell plugin that endeavors to provide a fast and pronounced view of various git attributes when you are under the umbrella of a git repository. Its main feature, the 'info bar' (information bar), displays the following information: current branch (in 'red' if on master); current cksum (in 'red' if there are uncommitted changes, and an 'uncommitted changes' message in the message area); and stash count in the message area if you have stashes. It includes an install script and removal scripts. It is currently only tested in Bash, GitBash and ksh93. It was previously named 'bash-git', but the name has been transitioned to 'git-info-bar', as a long-term goal is cross-shell compatibility using a Perl back-end.
documentr is a Web-based tool for editing and presenting software documentation. It allows you to easily maintain documentation for multiple products and product branches. Edits can easily be copied between branches, with merge conflicts being handled gracefully. It uses Markdown as its markup language, along with some extensions, and has a role-based permission system.
gitg targets cases where it is useful to provide a graphical representation of Git data or actions. The history view is a good example, where graphical representation helps to get an overview of the repository. gitg does not aim to be an advanced tool that allows access to every feature of Git through a graphical interface. However, it will try to incorporate common actions that might require multiple actions on the command line (like staging, unstaging, reverting, and committing).
GitFS is a fuse- and git-based remote filesystem with local cache for disconnected operation. It does periodic commits and pushes/pulls to keep a local shadow file system in sync with a remote repository. The filesystem should continue to work when you are disconnected. Merging after disconnected updates from multiple locations is left to git.