Stumbled into Jon Udell’s Library lookup bookmarklet and thought I’d give it a spin. It took some tweaking, but now I’ve got a Seattle Public Library/Amazon Bookmarklet
To use, just drag the bookmarklet above to your toolbar. Visit Amazon, search for a book, and then click on the bookmarklet. It’ll check the availability of the book in the Seattle Public Library.
RoBlaBlog 
Nice. That kicks ass.