We use IE7 at NASA (along with Firefox on our Linux side). But at my last job, we used IE6 and wrote web applications that had to run on IE6, because that is the only way several of our scripts would run… because they were basically exploiting security flaws in the browser. There was a big hullabaloo about the “possible switch” to IE7 and what it would do to the web applications in force for most of the company. The final decisions as of Nov ’08 (when I left)? Stick with IE6 because trying to come up with the right way of doing stuff would be far too much of a hassle. To be fair, these browsers only worked on the intranet with no outside access (except for developers [laughs evilly]). But still, having it be official company IT policy to use IE6 because of (as opposed to in spite of) the security flaws that exist was pretty entertaining.