I've used Secondbar for years and recommend it. I'm currently using it with 10.8 but have used it with 10.7 and 10.6. The only downside IMO is that it only mirrors the application menus and system time. It will not show system icons such as WiFi, Bluetooth, Time Machine, etc.
You can also rearrange and resize windows quickly by right clicking on the red/yellow/green buttons (X - +) of any window. This is useful when connecting a laptop to a display and the OS not remembering where you previously had windows. I have some AppleScripts that automate this as well if you're interested.