By tracking the active request phase, it can be displayed by mod_status and can provide a quick guide to where work is piling up, since 'W' doesn't help much when some of the phases covered by 'W' are much more fragile than anything Apache does.
Here's a sample mod_status view: http://httpd.apache.org/~trawick/active_phase.jpg
+1, very cool.
An initial patch is at http://httpd.apache.org/~trawick/active_phase.patch. mod_status may need to require a query option in order to spit out the new information.
I think extending ExtendedStatus to take [time,uri,module,phase] or something like it might be the best route. ('on' could easily set options for backwards compat).
I agree that knowing the actual module name would be the most helpful... But I am not sure of a clean way yet.
-Paul
