This panel mount Toggle Switch has built-in indicator lights so you know when the switch is on. They mount in a 20.2mm diameter hole and are rated up to 16A 12V. These SPST switches have three terminals, the two of which you would normally see plus one at the blue LED. Although these are for 12V, the LED only works on 5V.

This small On/Off/On Round Switch up to 10A at 125V AC can be mounted on a panel with a 20mm diameter hole. It will also look very elegant in your project.

This small On/Off Round Switch up to 10A at 125V AC can be mounted on a panel with a 20mm diameter hole. It will also look very elegant in your project.

A Pedal of Metal. This is the same type of Pedal you might find on a tattoo machine or as a damper pedal on an electric piano. The non-slip pad on the top and rubber bumpers on the bottom prevent the pedal from slipping out of place during use. If it opens, it's a simple switch and a big spring. This Pedal, however, has been described as "elegant and generous" and I think we have to agree.

MP3 Player Shield - SparkFun