StudentAdvantage.com sells discount cards that students can use to save on various vendors. The card costs $20 and there are a lot of opportunities for students to save much more then that through discounts.
T-mobile discount of 12% on recurring charges. So if you have T-mobile cell phone you get 12% off your bill. For a basic $40 monthly service that would be an annual savings of $57.60.
Amtrack and Greyhound both give 15% off fares. So if you spend $100 to take a bus home for Thanksgiving then the StudentAdvantage card would save you $15.
Target.com offers 10% off online purchases. Drugstore.com gives 15% off. Office Depot also gives 10% off.
You can see the full list of discounts StudentAdvantage offers here.