No, black cats are not unlucky!  My family has a black cat right now, and he's the sweetest thing!  The only real problem we have with him is his tendency to bolt out the front door and hide under the neighbor's porch every now and then.

We got Kohl (the aforementioned black cat) when we were getting our car fixed.  Mom was sitting outside the building, waiting for the car, and this little black kitten came up and started purring.  So we took him home.