Mainly because I wanted to futz around with the Google Maps API, I’ve created a mashup that pretends to lay out all the shelves in Harvard’s 73 libraries on a map.
You can choose your starting point — it defaults to Widener Library at Harvard — and choose whether you’d like to see a line of markers or concentric circles. It then pretends to map the shelves according to how many books there are in each subject.
Here’s where the pretending comes in. First, I have assumed that each book in the 12,000,000 volume collection is one inch thick. Second, I have used the Dewey Decimal system’s ten subject areas, even though Harvard doesn’t use Dewey. Third, I used an almost entirely arbitrary method to figure out how many books are in each subject: I did keyword subject searches. Sometimes, when the totals seemed way too low, I added in searches on sub-headings in Dewey. At the end, the total was probably closer to 4 million, which means my methodology was 300% unreliable. (Note: Math was never my strong suit.)
So, the actual data is bogus. For me, learning how to use the API was the real point. If you happen to have actual data for your local library, you can download the page and just plug them into the array at the beginning of the page. (All the code is in the .html file.)