https://github.com/pkazmier/snippet.el.git
git clone 'git://github.com/pkazmier/snippet.el.git'
The original Emacs Snippet Mode. I wrote this code years ago to replicate TextMate's snippets in Emacs. It was my first real undertaking in Emacs Lisp. I post the code here for posterity.
This code is no longer maintained. Fortunately, the Internet has no shortage of others willing to improve upon unmaintained code. This codebase was used as the foundation for another project created by pluskid called smart-snippet. It has since been entirely rewritten by others and is now called YASnippet. If you are looking for a supported snippet mode, I'd recommend checking there first.