Switch between windows on Mac OS X?

Cmd-` toggles through the windows forward.

Cmd-Shift-` toggles through the windows in reverse.

Cmd - alt - arrowkey switches between tabs

There's a 3rd party app called Witch which will let you cycle through all windows of all apps.

Along with the other suggested shortcuts, you could always use Exposé.

On a recent MacBook, or aluminium keyboard, the 'F3' key is dedicated to Exposé. If you don't have a keyboard with an Exposé key on it, you can use 'F9' and 'F10':

• F3 or F9 to show all windows on the current space.

• Ctrl-F3 or F10 to show all windows belonging to the current application on the current space.

For even easier access, I use the four-finger upward swipe to activate Exposé.