Erdős Number is an individual's "collaborative distance" to Paul Erdős.
I calculated the "PG number" for everybody Paul Graham thanks in his essays.
I then recursively found their blogs, and extracted the people that they thank in their essays.
This is still a work in progress. The data is open-source and I'm continuing to add edges on Github (linked on the website).
You could use open data from Congress, and do this to present a "who introduced / co sponsored which bill" web. Probably get some commercial users of that if you wanted.