Trattoria da Pino, recommended by our B&B, was a great locals place. Very cheap with a working-class clientele, and lots of fun.
Pizzeria La Duchessa di Citarda Giada has good pizza as well as other dishes. Mostly tourists, but still inexpensive and good quality.
Sapori Perduti had a lovely and somewhat fancy atmosphere, but the food, while good, was disappointing for the price.
Ciuri Ciuri is a bar ("cafe" to us Americans) with delicious arancini and other local specialties - highly recommended.