I have to use IE6 at work, and I'm surprised at how much of the Web is simply broken for me. It's kind of bittersweet.
It was a very grim time.
Fortunately, a number of web developers held out of a viable alternative to a Win32/IE monopoly. When Firefox was finally good enough for general use it was embraced by many web developers, Google in particular. By 2005 many prominent new web sites (Gmail and Google Reader, for two) took special care to support Firefox from day 1, something that was would have been unheard-of only a few years earlier. At that point it was clear that Microsoft could not win the browser war, and IE development languished.