You can buy at your favorite home improvement category killer store
that also has a pilot light
on it. Ours fits under a duplex outlet
cover, with the top position being the switch, and the bottom one a neon
The cool thing about these switches is that you can wire them so that the light is on when the light is on, or off when the light is on. Both have advantages. The first is how we have ours set up--the switch controls the overhead light on our back porch, which you cannot see through the door there, so now the indicator tells us if we've left the light on. Our next door neighbor would tell us that we left the porch light on all night sometimes. Hopefully, no more.
You'd use the other way if you had to find the switch in the dark.
A very useful item, and one that the average homeowner can install in a short amount of time. I, however, took a little longer because I needed a pigtail wire that I didn't have, so I had to drive to the friendly neighborhood hardware store to get a foot of 14/2 Romex cable.
Also note, this kind of switch cannot be used on a switch loop--you need to have a neutral wire in the box.