Add the WorldCat search provider.

<?xml version="1.0" encoding="UTF-8" ?> 
 <OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/">
 <ShortName>WorldCat</ShortName> 
 <Description>WorldCat provider</Description> 
<Image height="16" width="16" type="image/x-icon">http://worldcat.org/toolbars/firefox/worldcat.gif</Image>
 <InputEncoding>UTF-8</InputEncoding> 
 <Url type="text/html" template="http://worldcat.org/search?q={searchTerms}" /> 
</OpenSearchDescription>