Fly from San Francisco to Rome for $715 round-trip, including all taxes, on US Airways.
This fare is valid for travel on just a few dates in October and November. Found via Travelocity's flexible search (look for the $410 base fare). Also bookable on Orbitz, though this lower fare is "hidden" behind higher fares, so it requires a little clicking around. You might find it easier to just go with the flexible search on Travelocity.
Booking info in our fare details.