As part of a lawsuit settlement, Subway is to 142,000 California residents. You enter your name and mailing address, and they pledge to send you a $2 gift card if you are on of the first 142,000 people to fill it out. I’m slightly suspicious that they can’t shut the site down after receiving 142,000 entries, but it seemed legitimate when I went through the process. There is also a phone number you can call to claim your card: 1-800-964-1747.
Caveats: one per household. Expect 10-12 weeks for delivery.