This offer is valid for travel on flights between December 29, 2008 and November 11, 2009. All you have to do is enter SAVE35 in the Promotion Code box on the home page when booking your flight. $9 Fare Club members will then receive $35 off a roundtrip purchase when booking a qualifying flight! Non-members will receive $17 off.
This promo appears often, and this time it expires at 10:59 ET on Dec. 30.