If you click on Options (the wrench icon) up in the top right corner of the extension's pop-up window, you can set a tab limit for each window. You can search through open tabs, get the add-on to look for duplicate tabs, create custom groups of tabs, drag tabs between windows, and plenty more besides. Click the extension button and a pop-up window appears, giving you a favicon-based overview of all the tabs that are currently open, sorted by window. Then there's Tab Manager Plus for Chrome and Firefox.
Tab Manager Plus gives you a useful overview of your tabs.
