care to share some examples
Here's two for you. WinCustomize and WindowBlinds. Several State of Illinois sites function best with IE also.
Other reasons I use IE:
A: It is included with the OS I am running. I paid for it and can't get rid of it so I might as well use it.
B: It has proven itself to be reliable for the most part. Now that IE8 is playing well with my XP rig, I've stopped using Chrome.
C: It doesn't have or need weekly updates to fix problems. (which seem to create more problems)
As for security, I have never had any issues there either. I guess I'm just not paranoid enough.