When I run across a cool site, or some application that has aGitHub repo, I always do the following:

• Star the repo (obviously)
• Find the author(s) --> follow them!
• Fork the repo

This last item might strike you as odd. If I'm not going to contribute to the codebase, why should I fork it? The answer is simple -- finding things later. Let's say you found some great library for doing graphs on the web. You starred the repo, and bookmarked the link. But ... where is it? You search the web and it's lost to time and space. But wait! You forked the repo! You go look in your repos list and boom! You have probably a slightly out of date version of the code right there, with links to the original. Also - on more than one occasion - the original code is "gone". The repo might have been removed, or the user no longer maintains it. You have a copy that you can use forever in your own list of repos.

So, if you run across a GitHub repo that you even have a passing interest in, always fork it. And ... you never know you might be inspired to contribute back to the code base!