OPML is an XML-based format that allows exchange of outline-structured information between applications running on different operating systems and environments. With an OPML file you are able to add multiple feeds to your favorite feed reader, without having to add each feed url seperately. Most feed readers (like RSS owl, Google Reader) allow users to export their feeds in an OPML file and share them or import them in another reader. You can download our OPML file and see what we are reading (we read Greek blogs too, but the file contains only the those that are written in English), including Java blogs, tech blogs and news-based blogs.
You can get the official OPML icon or read about how it was created here.