In a loosely joined sort of way, I also use the SRU API to provide access to an index of a number of mailing lists, Code4Lib being one of them -- http://serials.infomotions.com/code4lib/  By submitting a query in the search box an SRU query is sent to the server, the query is processed, and a stream of XML is returned. This stream of XML is then expected to be rendered by the user-agent (Web browser) using a hyperlinked stylesheet. The result is a rudimentary HTML page. For example, a search for the word "hackers" in the Code4Lib mailing list archives -- http://bit.ly/p7AcYr

I also wrote a ExLibris Primo client in about 120 lines of code -- http://bit.ly/pX875w

Then there was an article a few of us wrote (Ralph LeVan, Ya'aqov Ziso, and myself) describing how to exploit a few OCLC Web services -- http://bit.ly/o3EwUb
 
Happy hacking!

-- 
Eric Lease Morgan