By popular demand:
To install, just drag the link to your bookmarks bar.
I made this for my friends in NYC:
Don't click on the link. Just grab and drag it to your toolbar.
How you use it:
1. go to amazon.com and find a book with an ISBN.
2. click on the NYPL bookmarklet.
3. it should open a page and search the New York Public Library for that book.
Have fun!