Book Cover Images

I’m looking into using book covers for a library website. Here are some technical and analytical resources I’ve come across:

The book Amazon Hacks has a simple approach for using product images from Amazon.
A conversation about using book cover images online, especially images from Amazon.
An article about how to properly use Amazon images.
Amazon’s Web Services Customer Agreement (see section 6.1), which says product images can be easily referenced/embedded with the ISBN, but via the partnership, there needs to be a link back to Amazon.
The Amazon affiliate program for information about link types. Under Product Links, it says that “we also provide Associates the option to host individual links themselves.”
A good Amazon beginner overview is at the Amazon affiliate program website.
The Amazon Associates Web Service, when used alone, must be used to drive traffic back to Amazon. This may not be appropriate for a library catalog.
A non-Amazon option would be to get images from the publishers, the bigger of which it appears have online systems for this. This would be Fair Use. Could these images be obtained via Amazon though? If so, they would need to be hosted on the user’s server, and they would not support the simple interface offered by Amazon.
Scriblio in action uses book cover images throughout its catalog that are linking internally but reference Amazon’s server.

I also saw some Amazon-related plugins for WordPress, although I ended up just using custom fields and code in the template to embed the images.