[moe]

Depends on what your frontend looks like. The average run-off-the-mill HTML site can ofcourse be made to work in all browsers with little effort. The real pain starts when you want to do interesting stuff. Advanced AJAX and javascript magic just doesn't work in IE6 without horrible overhead - partly due to the lack of sensible debugging tools.

[intranation]

Or... you could just use a Javascript framework that takes care of that abstraction for you. This is seriously not a hard problem.

[moe]

Well, frameworks go a long way but they don't help with the pains in the CSS area. When supporting IE6 you're generally limiting yourself to the capabilities of that browser. And for any non-trivial site you will run into hard problems regularly, unless you're leaving HTML behind entirely (ExtJS, Flash).

[kaens]

You can do entirely different fronts for browsers with different capabilities.

[moe]

Which is hardly a worthwhile option for a reasonably complex website.