I have been load testing a set of pages that access some off-site tracking
resources that I would like to leave out, since they are generating a great deal
of unnecessary latency that doesn't represent my own server load. 

I see that Enhancement request: 40933 hopes to address a similar issue, but I
think a more robust solution rather than filtering by "same server" (which
doesn't account for other internal servers that I would want to load test) would
be using regex to specify exceptions. 

That way, one could exclude any arbitrary resource defined by URL, inclusing
file extension, hostname, etc..