I understand that many students are trying to  earn a few bucks doing this and that. I guess you are looking for a part-time job, right?

As you might know, a lot of americans earn their living selling products in ebay. What most of these people do is buy goods at a cheaper rate in other sites/stores and sell them at ebay. But, you will have to be smart and should spend a lot of time online looking for such products. I know a guy who made around 700/800 in a week doing this while he was a student.
Selling books online is also a profitable time job.( Having seen bookstores rip off students, I even started a campaign to exchange books between students and avoid bookstores).I used to do this in my school days. I used to buy cheaper books from different online stores and sell them on amazon or ebay. This is a seasonal job, but since people start looking for books right after new year, this can be your quick fix. But, you should know what books are in demand. Research your school or ask your friends in order to increase your potential market size.