|OPML is what you can use to send all of your RSS feeds around to people. So if someone asks you “what RSS/Atom feeds do you subscribe to?” You can now just send them your exported OML file from Thunderbird.
To see the feeds I subscribe to and basically “get information” daily you can use my opml file here. If you save that file with your browser just open Thunderbird and in the News & Blogs section click “Manage Subscriptions” and then you will see an Import option. This is only available in Thunderbird 1.5+.