MetaCPAN is a service to search the CPAN repository of Perl modules. Perl programmers can search MetaCPAN by keyword, module author or category. The MetaCPAN service is also made available via API (and yes, there's a CPAN module to access MetaCPAN).
Developers can search the MetaCPAN API by six different fields: author, distribution, favorite, file, rating and release. There is also an advanced feature to join across multiple search types.
The API is RESTful, with data returned as JSON or JSONP with a callback.