Keep an eye out at Heiwa Dori — you're bound to come across some treasure or funny trinket among the stalls here. After you've admired the wares, try some fare from one of the food vendors.
Situated in Naha City Centre, this community marketplace is worth a look. But you'll find a great deal more to discover in this area. Kokusai Dori, University of the Ryukyus, and DFS Galleria Okinawa aren't too far away from Heiwa Dori.