The mysterious and exclusive Black List is an annual list of unproduced screenplays that are making waves in development departments across Hollywood. Think of it as the slush pile from Heaven. Last December, LA Times revealed the history behind the name and its founder. The "Black" in "Black List" is to counter the connotation associated with the word (is that a little of Malcolm X I hear?). I agree that Black is Beautiful, although it's clear I have a bias.
If on the list, there is a high probably you might receive an option. Although, not everyone likes the idea of the Black List. Here is an blog article slightly critical towards it, as well as the commenters.
Films created from the Black List include:
Charlie Wilson's War
Million Little Pieces
Black Snake Moan
Dan in Real Life
We Are Marshall
..and many many others.