The Pastry Box: Browsers
It has been just over 10 years since I built my first website. 16 years old with a copy of Microsoft FrontPage Express installed by Internet Explorer 4. Cut ahead, I was delighting in the elegance of writing HTML; declarative, simple semantics, expressive enough to be inherently accessible; HTML is a most wonderful invention for the distribution of information to all. All accessed through this strange tool: The browser.
IE4, Netscape 4, a year or so in Seamonkey before Phoenix came out. Firebird, Firefox, dalliances with Opera, and eventually Safari.
The semantics of HTML, and additional vocabularies such as microformats, are all but ignored by browsers. The browser could collect for you a social history of people, not just an address history. The browser could collect the events you view, even as a corresponding Mail client collect collects iCal invitations for your attention.
You could look at modern browsers and conclude that ignoring rich mark-up like contacts and events is just part of a design trend toward minimalism; to be a bare canvas for the rich capabilities of modern web standards. However, in a decade of learning the web, I recall one of my earliest critical assessments: If I mark up a column heading in my code, why won't the browser allow me to sort the table? To this day, I'm still not sure that there's a good answer to that.