My own Shopzilla site

From official Shopzilla Publisher blog:

"
Hey Publishers,

At the request of several of your fellow JS-loving publishers, it is now possible to query our Catalog API and return a response in JSON or JSONP. While XML is a wonderful thing, JSON and JSONP should open new opportunities to those of you creating widgets, banners, and other snappy ad content.
While the default response format is XML, you are able to specifically request the response format using the below parameters in your query:

XML: =xml&callback=callback
JSON: =json&callback=callback
JSONP: =js&callback=callback
Release: June 2011
API Versions: Bizrate, Beso

The release of these new fields should not impact you unless you have developed a means of auto-generating your XML handling code based on the XML schema document for any individual service. If you have done this, you will need to update your schema.

Don't forget to follow us on Twitter for snappy release notifications! Upon release, you will be able to see an example result set returned with this new value through our Catalog API Interactive Documentation. In order to access this documentation, you will need to log in with your Catalog API Key & Publisher ID. Once you are in there, view any of the individual service resource sections. At the very bottom of any section, you will see a link "[ + ] show test form". This will allow you to test out queries, viewing sample responses.

As always, please do not hesitate to contact us should you have any questions.
The Shopzilla Publisher Team"