HTTPNetworkSniffer is a tiny, free, portable tool which can record and display the exchanges between a browser and web server.
The program provides plenty of detail on every request: the host name, method, path, user agent, response and response string, content type, refer, content and transfer encodings, server, content length and a whole lot more. And so this could be very useful for web developers trying to troubleshoot low-level page issues.
But regular web users may benefit from HTTPNetworkSniffer, too. If you're curious to discover the link to a particular video you're watching on a site, for instance, it may be listed in the HTTPNetworkSniffer report; paste that into a download manager and you might be able to grab a local copy, even if the site doesn't provide a specific download button.
However you're using it, the program is, like all NirSoft tools, highly compatible. It runs on all versions of Windows, 32 and 64-bit, from 2000 upwards. And as well as working with WinPCap and Microsoft's own network monitor, it can also use Raw Sockets, although these don't work everywhere. And if you're running Windows 7 with UAC active then you'll need to run the program as an administrator for this to work (right-click the executable, select Run As Administrator).
A simple packet sniffer tool which can give you an in-depth look at the conversation between you and any web server