Yes, I know, funny name. In spite of what you may be picturing, it's actually a very nice little playground! LB and I headed over to meet our playgroup here a couple of weeks ago, and it was so nice we decided to take Mike back last weekend. Highlights are a bigger playground for the older kids, a mini-one for the little guys (with the spongy blacktop), swings, and lots of running space. And as an added bonus, the playground is under the airspace for Dulles International Airport, so there are lots of planes flying over! Chloe was very interested and would point up in the sky each time she heard one coming.
So, I couldn't find a website for the park, but I'll give you some directions: Heading West on Pope's Head Road from 7100, turn left on Quiet Brook Road. You will see the tennis courts and then the parking lot on the right. The playground is just a short walk down the path to the playground.
Definitely give it a try!