Online surveys, or selling things on ebay would be the most common. This blog has a few good site you might want to checkout. http://makemoneyonlinethetrueway.blogspot.com/
MLM is a good business concept. you need to check carefully any MLM offer becasue there are a lot of scams. but real companies with proven products like Nu Skin enterprises, Hearbalife, Avon are good...
if youre a girl, i would suggest babysitting.i would say that for guys too but people seem to think that guys babysitting their kids is somewhat creepy. so if you dont want to babysit, try yardwork,...