Here are some useful links to producing JSON and XML in various languages:
JSON for Ruby: http://json.rubyforge.org
JSON for Perl: http://search.cpan.org/dist/JSON/lib/JSON.pm
JSON for Python: http://undefined.org/python/#simplejson
JSON for ASP / .NET: http://www.newtonsoft.com/blog/archive/2006/06/26/571.aspx
JSON for JSP: http://www.json.org/java/
JSON for PHP (PECL): http://aurore.net/projects/php-json
JSON for ColdFusion: http://jehiah.com/projects/cfjson
JSON for C++ : http://jsoncpp.sourceforge.net
JSON for C : http://www.json.org/JSON_checker
To find futher libraries to handle JSON, take a look on http://www.json.org
XML in Ruby: http://libxml.rubyforge.orgXML in Perl: http://cpan.uwinnipeg.ca/htdocs/XML-Writer/XML/Writer.html
XML in Python: http://pyxml.sourceforge.net
XML in ASP: http://msdn.microsoft.com/msdnmag/issues/0400/cutting
XML in JSP: http://java.sun.com/developer/technicalArticles/xml/WebAppDev2
XML in PHP5: http://www.php.net/manual/en/ref.dom.php
XML in C++: http://www-128.ibm.com/developerworks/xml/library/x-serial.html
XML in C: http://xmlsoft.org
JavaScript reference: http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide
I welcome any suggestions, comments, links to websites using the library and your own personal examples to help new comers pick it up with great ease.