Using caps lock key instead of right click (contextual menu)

You can use BetterTouchTool for this. Just create a keyboard shortcut which is bound to right-click.

There are to caveats, though:

• The right-click command will be sent to wherever the mouse is, not on whatever is focused via the keyboard.
• To bind the CapsLock key, you may need to use a combination of KeyRemap4MacBook (to rebind CapsLock to some other key), as well as PCKeyboardHack (to improve CapsLock rebinding support).

I'm not sure if there is any way to invoke the context menu on the focused element rather than wherever the mouse is. However, if you do find such a way to do this, you can use a combination of KeyRemap4MacBook and PCKeyboardHack to rebind it to CapsLock.

The 3rd party tool http://pqrs.org/macosx/keyremap4macbook/ seems to be able to do what you need to remap your keys.

One possibility is to remap Caps Lock to Control and thus pressing Caps Lock + left-click would open the context menu.

Sure, this doesn't remove the need for a mouse click, so the right-click might be a better solution :)