Black plastic

[Fauxnali]

Lately have been using Meguire's Hot Shine Tire Spray on all things black and plastic including running boards and under the hood.
I love the stuff, i use it inside the fender-wells as well.
Doesn't make the tires too shiny but a nice deep black.

 

[ericsalvas]

ditto on meguiar

 

[moab]

I think you guys missed this. Forever Black Bumper & Trim Dye Kit. http://www.autogeek.net/forblacbumtr.html

It actually dyes your plastic. Lasts way longer. And costs $16.