Made some software to explore the tag-triples idea a bit further. It doesnt attempt to do anything with context yet (although it does handle 'graphs'). It does illustrate the 'ease of metadata creation' that I want.
I've installed a copy here for demo purposes (this is a temporary URL and may disappear at some point). BTW, I've noticed that the python executable on the hosted server keeps crashing - not sure why. If you get a 500 just refresh.
I've also uploaded a release of the software at sourceforge. I don't expect anybody to want it, but it's good discipline for me to make things releasable.