Beyond selling notes, most college students write papers…lots and lots of papers. Don't let these assignments go to waste. There are services that will buy your old college papers. For example, you could look at GradeSaver. This services allow you to sell your old essays and get anywhere from $15 to $100 for them. If you're writing multiple papers per semester, this could be a great little side income.
As for other tips, all I can say is “a penny saved is a penny earned”. If you are running out of ideas to make money, start saving. Some quick “low hanging fruit” tips to save some quick cash include – switch to MetroPCS or Boost for cellphone (I only pay $20/month), switch auto insurance to Insurance Panda ($25/month), and start using GasBuddy (saves me like $100/month at least. I drive a lot).
This kind of work is executed in almost every city, and we call them ‘retail shops’. So, here we will come up with the same in our college, a tip for this is; ‘wholesale market’. Buy a bulk of stationery or any other stuff you think that can be used in your college and would be of major use to the fellow survivors, and sell it for the market price or a little less if it brings profit.
Search for freelance writing and editing gigs. The rates for these jobs vary: you may be paid by the word, be offered a flat rate for a project, or in some cases can be paid an hourly rate. You typically won't be able to retain copyright over your work or collect royalties, however. Even so, by doing freelance work you can build a portfolio and make valuable connections which may later pay off with more stable job opportunities.