Display an OPML reading list on your page. Could be an interesting way to show trackbacks, along with the obvious cool blogrolly sort of thing it can be.
Convert Powerpoint to OPML. This could be great for aggregating presentations from graduate classes.
How to use Dave Winer’s OPML editor to post to your wordpress blog.
Interesting set of top ten lists – sources on politics, travel, tec, biz, etc. Seems hand-picked, which I don’t like, but I’m getting quick previews of feeds I might want to subscribe to, which I do like. Complimentary OPML included.