Paul Graham wrote an essay back in 2009 entitled “The List of N Things”:
I bet you the current issue of Cosmopolitan has an article whose title begins with a number. “7 Things He Won’t Tell You about Sex,” or something like that. Some popular magazines feature articles of this type on the cover of every issue. That can’t be happening by accident. Editors must know they attract readers.
Why do readers like the list of n things so much? Mainly because it’s easier to read than a regular article. Structurally, the list of n things is a degenerate case of essay. An essay can go anywhere the writer wants. In a list of n things the writer agrees to constrain himself to a collection of points of roughly equal importance, and he tells the reader explicitly what they are.
After reading this essay I distinctly remember getting an idea for a web app immediately. Although only now I realize it has been 5 years since that essay came out, it was only last week that I decided to use the spare 3 days left in the week after a vacation to actually build it. I challenged myself to build the whole from scratch app during those three workdays (altogether 20 effective hours).