Ask HN: How do you keep track of new libraries/projects

I've been developing with Ruby for several years, and sometimes I fall in the trap of thinking that I know what the right tool for the job is, especially when we're talking about plugins and libraries. Yet everyday I stumble across new libraries that are better and are already followed by hundreds of persons that I didn't ever hear about.

Now I'm wondering how you hackers keep track of new libraries and projects. I'm particularly interested in Ruby and Rails projects but I think the discussion would benefit from a more general approach. Do you subscribe to some rss? Some aggregator like rubyflow.com? I'm curious to hear what you do.