I recommend going down to the bare minimum and sometimes it helps to consistently compare your site with web standards compliance. I can understand some programmers' dilemmas which arise when IE doesn't support 90% of CSS, but at the bottom line 65% of users work with IE and it's the professional-grade standard for most businesses, nonprofits, and schools.
That's just my viewpoint on the issue, but I know some people have made their applications browser-specific, in which case they take advantage of available add-on features or applications to enhance the website and allow the use of more advanced templates/designs.
http://socialdecks.com/iMotable/