While there are a plethora of little shops along the way, you might also want to check out a few of the museums along that route.
As stated, there are several shops on Chincoteague Island. While ther, check out the Refuge Waterfowl Museum. One of my favorites, it's located about fiteen minutes off of Route 13 at 7059 Maddox Blvd., (757) 336-5800. Take Route 175 , (Chincoteague Road), East at T's Corners. Might want to check their hours first though.
A little farther North look for The Ward Brothers Museum in Salisbury Maryland. It's located just off of Route 13 in Downtown Salisbury Maryland. 909 South Schumaker Drive. (410) 742-4988. Can't miss the signs. A great carver's museum. I actually know someone with several carvings on display there.
Again a little farther North, in Cambridge Maryland, look-up Chesapeake Classics. 317 High Street, Cambridge, MD., (410)-228-6509.
Even farther up North, if you want to wander a little off of Route 13, check out the Havre De Grace Decoy Museum in Havre De Grace Maryland. Located at 215 Giles Street, (410) 939-3739. It's probably one of the bigger museums along the route.
Hope these help a little.
Have fun,
Jon