I had to attend a conference in Rome last Thursday, and had my wife join me for the week-end. The culinary side of the visit was very much based on input from this site. Thanks a lot to everybody who has contributed.
On Friday we had dinner at Antici Arco. The food is excellent, they have a very impressive wine list and the service was very nice and friendly (if a bit chaotic). I can definitely back-up earlier recomendations.
On Saturday we ate at Checchino dal 1887. This restaurant is not for the squeamish as it relies heavily on the "fifth quarter", but the food is great. We went for their Menu Historico and it was great. Again, this restaurant also has a wonderful wine list. Testaccio is the week-end playground of Rome, and a vist to Checchino dal 1887 can be combined with a visit to any of a number of funky bars for a drink (or three).
I look forward to going back to Rome.