If you're an artist and have a knack for graphic design, you could do online design work for websites and businesses. This could be everything from making small graphics for advertisements to full site redesigns. To get started, check out a site like 99Designs, where you can enter design competitions and if you're selected as the winner, you get paid.
If you have anything you don't use anymore, and it's too large to sell online, Craigslist should be your go-to place to sell stuff. In college, you may want to sell all your furniture before moving home from school at the end of the year. Depending on what you own, a few $100 might be better than storing it or transporting it back with you. It's easy to setup a listing and sell anything on Craigslist.
Watch for emails asking for note-takers. Once a fellow students' needs are documented, disability services will contact the professors and ask for volunteers in the class to take notes, and your professor will in turn email the class. You can also upload your notes to a platform like Stuvia, where you can earn money by selling your notes to other classmates.