You know the few websites out there; they do checks on operating systems and say that you need to be running a version of Windows to comply with the website. While that number doesn't seem so high today, there are still a few that do.
Take the Staples store website for example; I tried to fill out their job application through Firefox on Ubuntu, turns out they check out for anything not Windows. I tried a Firefox application that tried to "trick" the website into thinking it was a Windows browser; that didn't work out either.
So I installed ie4Linux. It's flash content didn't hold up so well for me, so I went to the Staples website until I got to the point of it saying my OS wasn't compatible, copy and pasted the URL into ie4Linux, and suddenly I was running compatible software! Who knew, right?
So how many times has ie4Linux gotten YOU out of a jam?