Thanks for the suggestion, I like how succinct it is.
monitors.txt's purpose isn't to replace testing new features during development. Monitors.txt replaces the process of logging on to a 3rd party's app to configure the monitoring for the new feature.
This syntax seems a lot less confusing and more powerful than the subset of English presented.
Another bit of syntax that I think is missing is something like:
GUAGE:
http://domain/stats/logins 60s
COUNTER:
http://domain/stats/logins 60s
AVG:
http://domain/stats/logins 24h
Something like this would allow you to setup not only with simple external monitoring systems, but with internal systems like Nagios, Ganglia, ZenOSS, etc.
Of course, I do have to agree with many people that I am a bit uneasy PUBLISHING all of this data for all to see.