Here is a little ad box on the Slate website. I dare say that almost anyone on the planet with access to a computer will recognize the reference to Facebook, Google and Apple.
A single letter of the alphabet is all it takes to evoke Facebook and Google. In the case of Google, it is not even the first letter of their logo.
The Google "g" is a typeface called Catull, designed by Gustav Jaeger in 1982 for the Berthold typeface foundry. The Facebook "f" is apparently based on a font from FontShop. The Apple apple takes us somewhere else, but few corporations have made such effective use of typefaces as Apple. Think of "Apple Computer Inc." (Motter Tektura), "Think different" (Apple Garamond), and "iPod" (Myriad).
Such is the magic of typefaces, that twenty-six letters can be recognizably rendered in so many ways. And such is the magic of computers that each of us has access to a virtually unlimited variety of fonts.
I love the crisp typeface (Trebuchet; or is it "tres beau, Chet"?) that Tom used for the posts on this website, black on white. No nonsense, easy to read. And his choice of typefaces for the header is smart: The "Science" font (Euclid) evokes the familiar logo of the journal Science. The "Musings" font (Bradley Hand Bold) -- well, it has a musing sort of feel, rather more private and idiosyncratic.
For my own writing I once preferred Palatino, then American Typewriter. These days I compose in Lucida Grande. I suspect the fonts trace an evolution in my relationship with my work, or perhaps in my attitude towards life. Surely by now someone has written a book analyzing a person's character and personality according to the typeface(s) and size(s) they use on their personal computer. A Palatino guy is a different person from a Lucida Grande guy. Exactly what the difference is, I will let you decide.
It would be interesting if the comments here showed up in the font of your choice. Could we recognize the usual suspects from the typeface they use to communicate?