I recently had to debug a script that makes invisible image requests for metrics tracking purposes.
The browser doesn't really give you a a clue what it's doing in this case, and putting in alerts or writes actually changed the behaviour (!!).
So I looked into getting software that logs and reports on outgoing http reqyuests from the local machine, hoping I could find something like a console that would run independantly of the browser. I downloaded and tinkered with a bunch looking for something that was functional, free, and reputable.
The one I ended up using (which seems to work great) is
HTTPLook.
charles is a reverse proxy that can be used for http monitoring and also connection throttling.
pageengage is a nifty and convenient plugin for IE. With a terrible name.
Dated: 10/27/2005