Iris.ia lets you paste the url address of any academic paper or TED Talk and then, in return, it provides you with a free interactive mosaic of related research papers.
I tried it with Dan Pink’s TED-Talk on motivation, and none of the papers that it linked to (and that I checked) were behind a paywall.
It seems like it would be very useful research tool.
And, in case you are looking for additional research tools, here are a few more that I’ve posted about in the past:
Author Path is a free tool to help university students write theses or journal articles. I had my daughter check it out (she just completed her Masters Thesis), and she says it would have been very helpful to her.
Let me know what I’m missing!