Zipcar is the world's largest car sharing and car share service. You can use a car by the hour or day without the hassles of owning or renting a car. There is $50 driving credit offer for new members. YMMV, since this promotion is targeted to NJ TRANSIT riders and I'm not sure whether it's open to everyone or not.
5000 Amtrak Guest Reward points sign up bonus is available for its Select Members but all members can earn 1 Guest Reward point for each $ spent on Zipcar.