If something on your system is running amok, or you think you might have a spy in your midst, or you're simply curious (or obsessive) about the inner workings of your network, give this simple program a look. TCPView presents you with a very simple interface that is appropriate to its purpose and relatively easy to use. You get a list of the TCP/UDP connections on your system, and the ability to interact with specific connections or the process that created them.
The list auto-updates as connections are created or destroyed, so you can see your network activity in real-time. If a particular program--or perhaps malevolent bit of spyware--is streaming data from your system, you'll be able to see it, and, with the handy context menus, either close the connection or end the process. If there's a lot of activity on your system, you can filter the list. You can also save the entire list to a text file, and alter the speed at which the list refreshes.
We couldn't get the included Help file to load, but the program itself seemed quite stable. The download comes as a ZIP file with no installer, and there are two executable files in the ZIP, which may be a tad confusing. Since there's no install, removing the program is as simple as deleting the files or directory you placed them in. TCPView is a great little utility that keeps it simple and does its job well.