I suspected that one could write a full OPML editor completely without server-side code, using some XSLT and JavaScript trickery.

The Hyperscope project has now done exactly that. It’s very cool. Try it out here.

They have applied it to something rather interesting in itself: a modern version of Doug Engelbart’s famous Augment system, which was shown at the "mother of all software demos" in 1968. A streaming version of the demo is archived here and if you are interested in computers, you simply must have seen it. Almost 40 years later, we still don’t have all the features that Engelbart had working in 1968!)

But back to OPML: what Eugene and friends have accomplished there not just works but even looks pretty; it also appears a lot more usable than many server-based OPML renderers. If I understand this correctly, the only thing one has to do to render OMPL through their code is to add a single line (<?xml-stylesheet ...) to the OMPL file.