Very handy little tool that if you don't want to kick open Network monitor to do a quick trace to a web server etc, or you just want to quickly see what headers are being set, when accessing a particular page.

Its called Fiddler.

Its based upon the .Net framework 1.1 and acts as a go between Wininet and the web server. Essentially capturing all the network track sent and recieved by Wininet.

Check it out on MSDN at:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwebgen/html/IE_IntroFiddler.asp