This is a very small crag with only a handful of climbs, but it's worth visiting if you are climbing at French's Dome. All the climbs are bolted and range from 5.5 to 5.9. The Salmon River is right across the road (fishing?).
Take rte 26 to the town of Zigzag. Go south ~4 miles on Salmon River Road(2618). Salmon slab is on left and has a gravel area for parking.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Salmon River Slab: