Grazr is one of apparently several mini OPML browsers, but it's the one I've used so far and I like it. If you haven't seen it in action, check out the "my favorites" box in my sidebar. I think there are lots of different and interesting ways that this kind of tool could be used, so here's a list of ideas I've come up with so far (please feel free to add more).

1. When you create an OPML file to share with people, give them a way to look inside it by posting a Grazr box next to your write up of the file.
2. Have a blogroll on the side of your site? Save space and display more information by displaying your blogroll in a Grazr box. (I have.)
3. Planning an event someplace? Pack a whole lot of information about the event, its participants and its location all into one OPML file displayed in a box.
4. Going to a conference and want to share info with your loved ones? You could set up a box to display your flight schedule's RSS feed, your blog posts, flickr photos tagged for the conference, etc.
5. Have a project that you want to discuss that has multiple subsections with subsections therein? Put it into outline form and display it with one of these groovy boxes.
6. Create a list and let readers click through to the most recent photos, audio or text regarding each item in the list.
7. Schedule tasks with progressively more granular descriptions or instructions. Some people will only click through to see that Jane is working at 2:00, others may click through to see that she's calling Joe on the phone to talk about subjects A, B and C.

This list has infinite potential, but I've run out of time. You get the idea. Working with OPML outlines is going to get easier and easier and this new way of displaying them is a key step. Heck, this list could be elaborated on, have lots of details added, and work great inside one of these dynamic boxes itself.