I think passive income is about working smart rather than working hard. Take art, for example. Let's say you're a pretty good photographer and there's a demand for your work. What can you do?
Work hard: do portraits, become a wedding photographer, sell your photos in a galery, ect.
Work smart: submit your photos to a stocksite and earn money everytime someone downloads your work, make your photos into mugs, puzzles, calenders ect. and sell them all over the world through an automated site like DeviantART or Cafepress.
Instead of making new photos and selling them once, you can make one photo and sell it many times wiyhout lifting a finger. Rather than selling the tree, you sell its fruits.
