Shlemiel gets a job as a street painter, painting the dotted lines down the middle of the road. On the first day he takes a can of paint out to the road and finishes 300 yards of the road. “That’s pretty good!” says his boss, “you’re a fast worker!” and pays him a kopeck. The next day Shlemiel only gets 150 yards done.
“Well, that’s not nearly as good as yesterday, but you’re still a fast worker. 150 yards is respectable,” and pays him a kopeck.
The next day Shlemiel paints 30 yards of the road. “Only 30!” shouts his boss. “That’s unacceptable! On the first day you did ten times that much work! What’s going on?” “I can’t help it,” says Shlemiel. “Every day I get farther and farther away from the paint can!”
From JoelOnSoftware
On a side note, the link explains how really malloc works (linked lists of memory available actually), for the C programmers present 
I’d like to do more than repost stuff, but my other commitments are piling high at present 
Edit: there’s a really long page where a bunch of people tried to figure the maths of this.
