I'm a Web Application developer and as such supporting IE6 is a royal PITA.
At home most users have upgraded to a better browser or IE7 or IE8 because they can but at work many desktops are "locked down" by Corporate IT, thus users can't install their favorite browser.
I understand that IT Admins need to support a large user base and thus mass browser upgrades may cause headaches if a work related site or application doesn't work in IE7 or IE8.
Alas, the question is:
What Software Applications do your users need that require Internet Explorer 6?
(as a side note, for anyone with persuasion power... feel free to push these software vendors into supporting IE7/IE8/Firefox/Chrome so we can drop this 8yr old browser)
(Note: For this question i'm going to ignore PCs that can't upgrade to IE7/IE8 due to being Win2k PCs...)