My friend and I are trying to find some cars to fix and resell, but the only online listings that we can find that aren't full of brand new cars are ebay, craigslist, and autotrader. Are there any other decent online classifieds for used cars?

Many newspapers list their classified ads online along with their news. You could check the general area where you live and see what newspapers are published and see if their ads are online. You can sit in the comfort of your home and go through the ads. Of course you are only limited in scope of the search depending on how far you are willing to travel from where you are.