You will not find groomed blacks at Keystone. The only one that comes to mind is Diamond Back. Sometimes it is groomed sometimes not. As Vinn said there are some easier black bumps. I like the ones at North Peak, Cat Dancer, Bullet get little traffic. Also at Northpeak is Starfire, groomed blue, It has a nice pitch though last time I was there is was pretty skied off.
At the Outback there is a blue bump run that is lots of fun, Big Horn. It is easy to miss though. Go through the trees bear right and it opens up. Gets very little traffic.
If you want grommers though they are blue. On the Front Mountain, Wild Irishman and Frenchman have some fun pitches.
We will be skiing Keystone this Sat. If you are in River Run stop by Fritz Alpine Bistro. We are often in the corner swilling a Bass or a glass of wine.