So I've always been curious about the story of Goldilocks and the Three Bears. It fascinates me that there is a story for children about a girl who breaks into a home, rummages through the family's possessions, and indulges herself in selecting "just the right one" of anything she wants.
The saying goes "beggars can't be choosers," but apparently intruders can do whatever they want.
Nonetheless, the story is quite enduring. And it does appeal to me on a user experience level - the concept that everyone seeks the product that fits them "just right." Unlike, say, clothes that are tailored to a hundred different sizes and shapes, the Goldilocks story divides everything into three manageable categories - the two extremes and the one right in the middle.
When it comes to designing Web sites, I try to follow a similar triage.
Say you are trying to build a design for a particular process. There are probably hundreds of choices and different designs you can try. How do you narrow the field? I usually look at extremes.
First, take the process and suppose you have a "surgical user" - one who knows exactly what he/she wants and will drill right to it. What would be the fastest and most direct process?
Compare this with the "accidental tourist." Someone who happened upon the site and is, for the moment, interested in seeing what you have to offer. What would be the most engaging process?
Now apply the Goldilocks principle and aim toward the middle.
Next, apply the same principle to compare the "devoted reader of every footnote" versus the "60 mile-per-hour click demon." How much text do you put in the page to satisfy the extremes? Now - find the middle.
Next you could compare the "technically savvy" daily Web user versus the "Sunday driver." How much do you try and impress with the latest rich media without intimidating? Again - aim for the middle.
Depending on the specific application, the important "extremes" will vary. But by applying this principle, eventually a design that balances everything will emerge. It will likely blend the best and worst of everything and be the most generally appropriate site for your users.
Of course there is a down-side to applying this principle. During the discovery process you become very aware that you can only hope to please most of the people most of the time.