ADHN ("Attention-Deficient Hacker News") is a simple userscript that adds inline article summaries to Hacker News. It uses the Clipped API, mostly because that was the only summarizing tool I could find with an API that wasn't rate limited. In my experience, the summaries tend to resemble the first few lines of the article, which works great in some cases and abysmally in others.
I feel compelled to mention that I am primarily a systems programmer, and this is the first nontrivial JavaScript I have written. (HackMIT 2013 gave me a good excuse to try out this newfangled "web-dev" stuff.) As a result, it is a virtual certainty that I have done some things in a very silly fashion. I suppose that's the nature of a hack though.