A few weeks ago, when I was finally prompted to write up my EXIF to machine tags script, I parenthetically remarked that
ways of getting all predicates for a namespace, and values for a namespace (at least within a given user's photos), would have made my list for 'things you'd like to see in Flickr' if I'd felt able to get away with being so demanding
Funnily enough, a mere week after posting that, Aaron Straup Cope posted to the yws-flickr group, announcing exactly what I'd obliquely asked for: methods to work with the parts of all machine tags on Flickr. I set to work, and by that weekend had produced a machine tag browser.
Thanks to some coding help from Tom Insam and suggestions by Ryan Gallagher, the currently live version is a fair bit nicer than the initial version. The code is still a bit of a mess internally (there's far too much repetition), there are some bugs (values with full stops (or decimal points) in particular), and I still have three items on the TODO list.
Despite this, it's still sufficient for users to see that the astrometry.net system has been able to solve about 85% of the images it's processed; that three images have had an ImageMagick Lomo effect applied before upload; the names of Len Peralta's monsters by mail; and where people take screenshots in Second Life. In fact, I've been pleasantly surprised to note that the code.flickr blog mentioned it when Aaron launched machine tag heirarchies to the wider world.