cheat.sh is a pretty useful tool that provides a cheat sheet for all you need like Linux commands, programming languages and DBMSes. You can use it to display usages of a Linux command, a code snip of a programming language like code for looping an array with PHP. For the moment, it covers 56 programming languages(C, awk, bash, PHP, Python, Perl, R, Ruby, JS, Go, Swift...) and 1000+ Linux commands.

There are some things that you can do to make Git bash on Windows a powerful and easy-to-use terminal but not only one for Git. Although there have been a few wonderful solutions for replacing the Windows command terminal, such as Cygwin or Cmder, but you may don't want another new terminal. The things to make Git bash better include adding aliases for quick typing/navigation/automation, adding new commands for new utilities, etc.

In this article, you will see some useful Git bash tricks on Windows, like how to change drive, search command history, open an application, configure SSH, run bash scripts, open a file with Notepad++, speed up commands, etc.

LearnGitBranching is an online tool that provides an visual and interactive way to learn Git. It is a pure clientside application written in JavaScript, only an HTML page with some JS and CSS, there's no AJAX requests. Just open it in a browser and you are ready to use it. It offers various levels for you to challenge. See more on its GitHub repository.

2 apps to manage your code snippets in local machine: massCode and SnippetStore. Both tools are open source apps with different features. You can choose one according your needs.