HotkeyNet shows you the coordinates in its upper right window each time you click .... but only if you've loaded a script that has at least one hotkey with a mouse button in its trigger.

It does this for efficiency reasons -- it only loads a mouse hook when absolutely necessary, to avoid slowing your PC even a tiny bit.

You can load this hotkey if you need to:

Code:
<Hotkey LCtrl RAlt RButton>
<ToggleWin X Y>
That will never get triggered (unless you have three hands, because that's how many you need to press that combination of buttons), but it will cause HotkeyNet to load a mouse driver.