If you had a chance to rebuild the internet, what would you change?
TunaFish: Kill, maim and murder the insanity of "be liberal on what you accept and conservative on what you emit.". Instead, have a standard dtd, and if any site deviates even a bit from it, render flashing red text on the site that says "The developer of this site is an incompetent moron. You really shouldn't trust him or do business with him." Make implementing this feature required part of every web browser.