http://www.freedompop.com/ Bam. (Ignore the "free phone" gimmick. It's just VoIP and sucks down data rather than using the proper voice line.)
Now, here's how it works. First, you have to buy a device, and you are REQUIRED to keep a credit card on file in case you run up any charges. If you are in an area with Sprint 4G LTE (
click here, click the Data tab, and either zoom in the map or punch in your college's address; 4G is red), you can get 400 MB of data at no cost. For (I think) $4 a month, you can get 3G as well, as long as you pick a 3G+4G device.
You will need to disable a feature as soon as you buy a device, or if you pass 400 megs you'll have to pay up; I just have it disable the device if I ever hit that, therefore making it impossible for my card to get charged unless the service changes.