I'm experimenting with ways of working with the bibliography for the book. Take a look at
and you'll see references for every book or article I'm citing in Proof and Counterexample so far. In fact, the page
contains a version of all of my references I've ever used, together with a very large number of papers I haven't cited. (I've imported my big BibTeX database into citeulike.)
The neat thing about citeulike is the way that you can watch current journals and even other people's bibliographies. If you like, you can subscribe to the PnC Bibliography (just use the RSS feed on that page) or you could even sign up to citeulike yourself, and add me (or the PnC Bibliography) to your own watchlist.
I am watching the tag pnc on citeulike, so if you come across a reference you think might be appropriate for the book, if you tag it with pnc in citeulike, it will end up in my queue.
If you've given it a go, what do you think?