On some Roms (CM11) double tap the status bar - but the bar is quite small, so I am often not hitting.
Power Button Widget - creates a button.
Problem is: My homescreen is full. I can create an invisible button above another widget, but this is not always working (Holo Launcher HD)
Gesture with the activity of Power Button WIdget.
Holo Launcher force closes on my Nexus 4.
Are there other ways?