I had been putting off trying to grok OPML for over a year. There are the obvious things but after spending time with the opml.org outliner. (Painful and non-intuitive) I managed to get together an OPML file of what I am really reading right now. I went down to 24 feeds. I will begrudingly add more as the days pass. I am thinking of quitting using bloglines and start with a new newsreader as well to make sure I don't go and red the several hundred I have in Bloglines and Sharp Reader.
I pointed a link from Share Your OPML to my file and voila! There are some cool things about this site that is a different slice from the other services like Bloglines and Feedburner.
I am really interested in the shared updating of outlines ala Basecamp (no OPML isn't Basecamp but the shared space thing) and I think I got a glimmer of the power of synchronized information in a format like OPML.