I have been working a bit more on a semantic web client. I've started a simple XPath-like language for referring to RDF resources (RPath perhaps), so one can do something like "director/birthplace" to get the birthplace of a movie's director. You can use these expressions in XUL to bind to data. When the data changes or an expression changes, or the user selects items in the UI, the relevant expressions are recalculated. Thus, when a user selects a movie title, the movie info changes accordingly. Here is a picture of a simple movie viewer. No templates or JavaScript is used by the XUL file.

I also created a sample using Dan Brickley's Wordnet service which returns word definitions. Here is an image.

The hardest part is coming up with a name for this thing.