Got junk? Try posting online ads in your local area for stuff you're trying to get rid of. You will be surprised by how many people want to snap up great deals on items you may be throwing out anyways. Kijiji is a great site that allows you to post classified ads for free! Visit it today: http://www.kijiji.ca/
It's best to sell things that are in relatively good condition (no used underwear). My recommendation would be to find the regular retail price online for the item you are trying to sell and reduce the price by 20-60% depending on the condition. People who are browsing through the ads on Kijiji are generally looking for a deal so if you are charging the same amount it costs to get the same item new than you won't be selling it anytime soon. Try to be reasonable and you should be able to turn your trash into cash.
I was able to sell an old board game that I wasn't playing for $20. It's a great way to clear space in the garage or basement and earn a couple extra bucks. Kijiji is not limited to just selling items either, you can also advertise your skills and services such as tutoring, hair dressing, or any other trade.
Finally, you can browse Kijiji for free stuff. People are often trying to get rid of things like old furniture. As long as you can haul it away for them, you can often get it free of charge. So be sure to browse through the free stuff category periodically, it's a great way to furnish a dorm room.