The XML::RSS (Perl-RSS) module is a good place to start. There are some examples on how to use this module on perl.com and others are linked on the module's home page.

If you know XSLT, then you can convert RSS feeds into HTML that way too, XML::LibXSLT is a good module for this, and there is also XML::RSS::Tools which is a wrapper around XML::RSS, XML::LibXSLT and LWP.