I've found one of the best ways to do the "stubmleupon" concept is to follow dozens of devs who star interesting repos (sometimes solely for that reason) and check your news stream often. I follow devs from a wide variety of backgrounds, which yields numerous libraries that I might not otherwise be aware of (and sometimes months ahead of HN exposure). One of the best things I've done with my GitHub account.
How do you find these devs who star interesting repos?
Edit: after some thought and poking around, one way to find these devs is to just look at the profiles of devs who run projects you use. If they've starred a lot of repos, see if they star things you would be interested in. If so, follow them. Easy.
Your example is spot on. Additionally, I use twitter, authors of books, authors of research papers, see who these devs follow, and numerous other ways of traversing the GitHub social graph.
A solid example is: https://github.com/fogus