This is not my work, but it’s something I want to spread the word about. Somebody has created a site to list all the Unity-related projects on GitHub.
It is in beta, so there’s still a few things missing. Firstly, it doesn’t allow you to filter by licence yet, but that’s coming. Secondly, it doesn’t seem to preserve the formatting in the documentation/README. However, those are the only issues I have with it, and it’s an awesome tool. So, another place to look for snippets that might be useful when I get around to doing a new project.