The flipswitch section of Protean allows you to add any installed flipswitch to the status bar, so you can see when it's on or off at a glance.

Enabling the "Display When Off Instead" toggle causes the flipswitch glyph to be displayed in the status bar when it is not enabled. Using "Display When Off Instead" with the Ringer flipswitch is a great way to create a mute icon. No more forgetting that you left your phone on silent!