Chrome extension URL: https://chrome.google.com/webstore/detail/only-one-tab/ncglhpldleoholkdpodkalphmnhdlijf
This is currently a very alpha Chrome extension.
Do you often find yourself opening the same tabs over and over through the day and you end up with multiple windows filled with tabs?
This extension will automatically close any tabs that have the same URL as the window that you're currently using or opening in the background.