Due to numerous feature requests (hey Brian, hi Sven), I've added two features to Proxy Monitor: the possibility to set the proxy bypass list, and the option to disable notifications (balloon tips) when the proxy changed. So this is basically a small upgrade to version 1.1.
Proxy Monitor is a small application that monitors the network and auto-detects the internet proxy server to use. It can be started as a regular application, which will make it run as an icon in the system notification area. When started, it will auto-detect the proxy server to use. It will also automatically re-detect the proxy server when the computer’s network address has changed. The application can also be run from the command-line with the /detect flag to auto-detect the proxy and exit immediately (e.g. when the computer starts up).

You can download the tool below. Don't hesitate to contact me for suggestions or bug reports!
The ProxyMonitor 1.1.0 executable (101 KB)
You can also view the Readme file online.