United/Continental/AA Fare Sale SFO-ORD and ORD-SFO $160 total
Tons of dates in Jan/Feb/March. $160 roundtrip is a pretty good deal for these routes and you can even fly on UA 777s!
To see these fares on United/CO, go to continental.com -> Advanced search
Then select My Dates are Flexible
Choose a random date in Jan/Feb/March and you'll then see the calendar with what days the $139+tax fares exist.