Selling stuff on eBay. Someone who needs money could start by selling their own unused or unwanted goods and then look for products they could buy in bulk and sell on at a profit. A couple of our members have been doing quite well from businesses like that.
Freelancing is something else to consider for anyone that has a specific skill, such as writing, graphic design. There are lots of great freelancing sites and forums where you can go to advertise your services and to view project requirements posted by individuals and businesses.
If freelancing is not for you, you could try earning from sites like
MicroWorkers and
Amazon's Mechanical Turk.
Do you have any business ideas that thrive, even during a recession?