Until June 30th, get $25 off a future $100+ Southwest Airlines round-trip flight when you purchase a $100+ Southwest gift card  from Southwest.com using a US-issued Visa card. The Southwest gift card has no fees and no expiration date, so you can buy it now and use it whenever.
The $25 credit will be emailed to you and will likely be in the form of a credit voucher (I ordered a gift card but the credit doesn’t come for 4 weeks, but I’ve had credits before from canceled flights). Thankfully Southwest’s credit vouchers are like cash,
have no expiration date, and are usable on all flights but subject to these restrictions  (including blackout dates and an expiration date); so there’s no little risk of being screwed in the future (Thanks Ceo Reom!). I know a lot of other airlines’ vouchers are much harder to use, they’re specially coded and you can only use it on the worst possible seat of the worst possible flight.
$25 off $100 is a pretty good deal, that’s like being able to check in a bag at one of the other airlines! (have we upgraded from “nickel and diming” to “five and fiftying” yet?)
The fine print after the jump:
Offer only available on southwest.com. The southwest giftcard purchase must be made with a valid US-issued Visa card. Limit one fare discount per Visa cardmember and/or e-mail address. Visa cardmember will earn one $25 fare discount on a $100 or more single card transaction. Shipping and handling fees do not qualify towards the total transaction amount. The $25 fare discount will be sent via e-mail to the Visa cardmember’s account. A valid e-mail address is required to receive the discount. Allow four weeks after the conclusion of the promotion to receive the discount. The fare discount is good for a roundtrip flight purchase made between July 1, 2008 and August 30, 2008 for travel August 18, 2008 through November 19, 2008. Some fare restrictions apply.
(Photo by bracken )