Why oh why didn't I check this tool out earlier? While working on my hobby project I desperately needed as good network sniffer as possible. Quick Google search revealed a GTK based (so not originally designed to run on Windows) tool called Ethereal. Besides from looking very Linux-ish, the tool itself is incapable of packet capturing and needs WinPcap to function properly.

Don't let this steer you away. The UI is a bit quirky and it takes a few minutes to set it up properly. But after that you will be treated with a great overview of what's going on. Ethereal parses raw network traffic into high-level protocol data and shows it to you in a way that is way more easier than to stare at the hex values :) The screenshot below shows the level of detail available for a short Windows Messenger chat. Messenger is just one out of almost 700 protocols it knows!