I keep IE around because I do Web development - every once in a blue moon a Mac IE user will complain about something. Invariably it's an IE-specific problem (something broken on Windows as well as Mac); generally those I don't fix because I try to stick to standard code, as long as basic functionality is maintained for IE users.
Safari has run into trouble on a few sites, in my experience. So far Mozilla Firebird has been able to handle those.
I've run into fewer "IE only" sites in the past year; and when I do I complain persistently (and they will usually listen). I think it helps to point out that functionality doesn't have to suffer when they stick to Web-standard coding, since the IE-specific stuff has generally been written as an alternative to CSS/XHTML functionality, not to do something that can't be accomplished otherwise. Most of the time people are open to suggestion. On one occasion though it became obvious the Web "developer" only knew IE coding; in that case I tracked down and wrote a polite note to the person's supervisor. Eventually the site got changed (don't know about the site personnel though!).
Safari has run into trouble on a few sites, in my experience. So far Mozilla Firebird has been able to handle those.
I've run into fewer "IE only" sites in the past year; and when I do I complain persistently (and they will usually listen). I think it helps to point out that functionality doesn't have to suffer when they stick to Web-standard coding, since the IE-specific stuff has generally been written as an alternative to CSS/XHTML functionality, not to do something that can't be accomplished otherwise. Most of the time people are open to suggestion. On one occasion though it became obvious the Web "developer" only knew IE coding; in that case I tracked down and wrote a polite note to the person's supervisor. Eventually the site got changed (don't know about the site personnel though!).