Since the FBI's Contact Us page doesn't allow you to email them, here's what my feedback states. Not that they'll listen to it.
First off, you can stop using these terrible feedback forms. There should be hardly any boxes, and more textual input. There's basically two things that people need to refer to: content and design. That's it.
Your main page seems somewhat overloaded.
Your Most Wanted terrorists page goes to a stange place where I can't go back -- it should be incorporated into your other page.
You shouldn't use tables for design. Update to more CSS.
Your History page should include links to laws that have affected you.
It's shameful that you have no email address on your website. I wanted to send this to you personally.
Usually I'm more harsh in my criticism, but again, it's not gonna matter anyway. The feedback goes into the void.