We wrote a blog post explaining how it works (it's actually hard work to give good results), http://www.reddit.com/r/node_modules/comments/1msian/a_cleve...

One of the more clever things is that you can log in with github and then we use your github stars/follows to give you customized search results.

Did you try the search on VersionEye? http://www.versioneye.com/?ab=b

This is brilliant!