Corey Murata notes some nice lookup features for OpenWorldCat on Web4Lib today.
This prompts me to note the OpenWorldCat xISBN bookmarklet. We make a range of bookmarklets available, originally inspired by Jon Udell's library lookup. The innovation we have added is that we incorporate xISBN functionality, which allows the search to include all the versions, editions, etc, that we know about by mining WorldCat for items in the same work cluster.
We include an xISBN bookmarklet for Open WorldCat. This will take an ISBN from a page (for example, on Amazon.com), send it to xISBN to retrieve additional ISBNs if we know about them, and then searches for relevant titles on OpenWorldCat. Drag the following link to your toolbar, go to the page in Amazon or some other site, and click on the bookmarlet in your toolbar.
Drag this link to toolbar: OpenWorldCat
Fuller details are available on the OCLC Research website. There are also bookmarklets for a range of online catalogs and other systems.