Pipes

Pipes - a hosted service that lets you remix feeds and create new data mashups in a visual programming environment. The name of the service pays tribute to Unix pipes, which let programmers do astonishingly clever things by making it easy to chain simple utilities together on the command line

Plagger

Plagger - A pluggable RSS/Atom feed aggregator written in Perl. Everything is implemented as a small plugin so you can mash them up to build a new application to handle RSS/Atom feeds

earFeeder

earFeeder - will scan your machine for music and automatically detect your favorite musical artists. Once that’s done, earFeeder will generate an RSS newsfeed just for you