With HotKeyNet it is possible to do mouse-broadcasting, meaning that you can broadcast a mouse-click on a position in one window, to the corresponding position (regarding to window-resolution) in anoher window.
In WoW this is quite usefull for 'mouse-healing', using clique or healbot and for using targetet abilities, like blizzard, druids trees, hunter aoe ...

The general command to trigger a mouse-click with hotkey net is <ClickMouse ..> .
The command is quite compley, and better explained in the HKN-APi than i could do it here, so for real details you might look there .

I give here a simple example for simply broadcasting left, right, middle - click while pressing 'g' (for using 'g' as amodifier see <UseKeyAsModifier> ).

Code:
<UseKeyAsModifier g>
<Hotkey g LButton, MButton, RButton>  
<SendLabel w1, w2, w3, w4, w5>
<ClickMouse %TriggerMainKey%>
if you want tor also broadcast f.e. shift+left click you would have to add:
Code:
<Hotkey g shift LButton, MButton, RButton>  
<SendLabel w1, w2, w3, w4, w5>
<KeyDown shift>
<ClickMouse  %TriggerMainKey%>
<KeyUp shift>
Another example for this can be found here: [HotKeyNet] HotkeyNet + AOE!