The reverse lights on my car don't work... Well, more accurately, they work for a second. I pop the car into reverse and they flash and shutoff immediately. I've heard there's some switch that controls this...where is it located and how easy is it to replace? Thanks..it'd be nice for OTHER people to know when I'm backing out! I've almost been hit in parking lots twice because of this..

 

The device you are talking about would be on the side of your shifter. Assuming you have an auto. Not sure about a stick. There should be a black plastic "box" on the side of the shifter. It controls the backup lights,park/nuetral safety switch. I had all of this wrote down in my Haynes manuel but the bro-in-law kinda swipped it.
Not to sure if its hard or easy to replace.