Here they are:
Dino & Tony's Hostaria - Pizzeria
Via Leone IV, 60
This restaurant was actually recommended in a guidebook, although not under the restaurants section. It was a little sidebar in the Vatican tour section of Fodor's Pocket Rome guidebook. They recommended this place as a good alternative to the touristy places right across from the Vatican museums. They were right.
I've been here several times for lunch while visiting the Vatican. Both times have been superb, with great service and good renditions of basic Italian food. Don't expect to get a menu; the waiter just brings good food, like rigatoni bolognese, etc. Expect a bit of a language issue, since the waiter doesn't speak English; bring a dictionary and make do. Spanish should also work, since the waiter is from Argentina.
You're in Rome, so don't be in a hurry, and just have a leisurely lunch while they bring you food until you've had enough.
Piazza del Biscione, 92
This place is in a little square right off of Piazza Campo dei Fiori. If you stand at the statue of Giordano Bruno, turn to his 5 o'clock and head out the Piazza through that corner. The restaurant is in the little square, just on the right.
The food is pretty good. It's not the cheapest, but you'll get a good meal for the price. Check out the desserts -- there's a cake with layers of thin chocolate on it.
Corso Rinascimento, 71
This place is really worth visiting. It's one block of of Piazza Navona. Take the side street from the middle of the square towards Corso Rinascimento. Take a left, and it's right there. It has outdoor seating.
It's a bit pricey, popular with government types (the Italian Senate is across the street), but you get what you pay for, with great service. I'd recommend the Cace e Pepe' pasta, although other people had the Wine Risotto and that was very good.
Est!Est!Est! (Antica Pizzeria Fratelli Ricci)
via Genova, 32
I have not been to this place, but several of my colleagues tried it and said it was very good. I will have to try it on my next trip to Rome.
This restaurant has a number in it's name. This is a basement level restaurant on Via Palestro between Via Gaeta and Via San Martino della Battaglia (near Termini station). I wasn't impressed by the main dish, but I did get to taste a bite of the Tiramisu. It was the best Tiramisu I've had in my entire life. Hands down. We tried to go later just for dessert but it was "feenished". It's worth the trip for the Tiramisu; maybe lunch, before it's feenished.