ActiveRender which is a "plug-in rendering tool" for Userland Radio also has an external API and the ability to feed it an OPML URL over a standard HTTP call, that you can then get it displayed in your browser.

You take this URL:

• http://api.activerenderer.com/activeRenderer/render/?src=%5BINSERT HERE]

And in the [INSERT HERE] I put in:

• http://sholden.typepad.com/weblog/opml/TRTO_014_ShowNotes.opml

And you get this Active Renderer OPML view.  You can also use other people’s templates like Adam Curry’s for this kinda of look.

UPDATE:  There is a php OPML tool in the works.  It can be called remotely by adding "?url=[full uri]" to HTTP call.  My OPML above looks like this via Mike Montalvo php tool.