USB Guard is completely portable, so you don’t need to install anything to run it. Just start it up and it sits in your system tray and monitors the external drives plugged into your machine (you can set it to monitor specific drives if you wish). If you go to shut down your computer and one of those drives is still plugged in, it will show a prompt, reminding you to unplug it before you leave. That way, you’ll always have it with you, wherever you go.
USB Guard is a free download for Windows only.
USB Guard [via AddictiveTips]