I believe the other ways happymat27 was talking about were mentioned by sparticus, you can use different materials with high reflectivity. Personally I prefer the Mental Ray Renderer so a lot of the time I use the Mia_material_x

Remmy, a chrome shader is essentially a dark shader with very high reflectivity, of course, if it doesn't have any environment to reflect, it won't look too great. I had to dig this up from these forums, I lost the original in a Vista mishap :/. This was using the mia_material_x with a couple of light cards. You can easily get a mirror material by ditching the reflection blur I have on them.