There are random camp sites all along Stanley Creek Road and Rock Creek Road. Rich Mountain Road (FS338) may or may not be open. If it is, there are a bunch of sites along it as well. Same for FS259.
These roads are all to the south of Aska Road.
You could also probably park in the lot at either end of the Stanley Gap trail and camp up in the woods a bit too. Same for the Flat Creek Trail lot.
That would all be primitive camping though, no bathrooms or water.
As far as actual campgrounds, I believe there is one on Lake Blue Ridge. If you're heading from Blue Ridge, toward the Aska Trailhead, it's on the right. There should be a sign for it. The boat ramp is on the same road.
Here's a general map of the area. Drag it around
http://trails.firstworks.com/trails/trails.cgi/default/trailsystem.html?trail_system_id=26