Excellent work, and a really useful resource that goes straight onto my bookmark list...
But it's not enough. Personally I think, what it needs is a RESTful interface, or a SOAP/WSDL interface. I don't care which, I just want to build this into existing web sites all over London... But there isn't one. Just a web page.
So, six out of ten for effort. two out of ten for execution.
Think that little bit further guys. Take a look at the Amazon API and try again.