I checked out some esoteric books and every now and then would look through the previous due dates and wonder how much in common I may have with some of these locals I'll never know about. It's easy to meet likeminded folks on the web and yet with locals who've checked out physical books, there is that identity disconnect--in some cases for good reasons(I don't want everyone to know about every book I've been checking out).
Have you considered leaving something in books you check out? "Hi! I live nearby and also am interested in X! You should email me at ..."
Not sure how well your library checks things that you return (I know someone at Stanford who got an email from the library because she forgot to remove a couple sticky notes from a book), but it might be worth a try.
My wife found a piece of bacon in a library book recently, so I'm inclined to think that in general they don't check books often. Just stick a note in there.
I've found a few interesting things inside library and second-hand books.
Probably the most interesting was inside a library copy of the 2003 edition of the Clocksin and Mellish book Programming in Prolog. Inside the book was a print-out (dot-matrix, by the look of it) of an email sent in 1988 from one of the authors of the book to the other, regarding how to revise it for a future edition.
Edit: Also on the piece of paper, handwritten, is the name `Geoff Goodhill'.
