To compare the list of running webservices with the list of all active proxy definitions, currently one needs to log into tools-webproxy, connect to the Redis server and list the keys (and then compare it to the output of qstat).
It would be much nicer if this list would be available directly from nginx. For starters, composing the list by just naming the prefixes should be a) enough and b) not cause any security concerns. This should look something like this (http://tools.wmflabs.org/?some-magic-url):
bub dschwenbot pathoschild-contrib […]
Optionally/additionally, http://tools.wmflabs.org/?some-magic-url.json would produce the list in JSON format.