Easy PIL question

[Adam W.]

I know there is an easy way to do this, but I can't figure it out, how
do I get the color of a pixel?  I used the ImageGrab method and I want
to get the color of a specific pixel in that image.  If you know how
to make it only grab that pixel, that would also be helpful.
Basically I'm trying to make a:
if pixel == color:
    do_this()
else:
    pass

And have it do this as fast as my pc can handle (that is why only
grabbing 1px would be helpful)