Is there any software or tool that can give ⌘+` a visual interface just like ⌘+tab does?
3 Answers
You can set keyboard shortcuts for this (and more) in Preferences / Mission Control / Application windows.
control⬇ works for me in Lion but I'm not sure it's the default.
Currently there is no option in OS X to give ⌘` a GUI interface. However, you can switch windows of an application using App Exposé.
Go to System Preferences → Trackpad → More Gestures and enable App Exposé.
Use the gesture to evoke App Exposé.
Alternatively, you can install Witch:
Well now I know an app called HyperSwitch which can achieve this. It is produced by the vendor of HyperSock.