Back in the day, the G-men had style.

According to Wikipedia, boaters "were supposedly worn by FBI agents as a sort of unofficial uniform in the pre-war years."

I for one think the world would be a better place if this tradition were to be revived. To give it a modern twist, they could match the color of their hat bands to the current terror threat level. I realize this could lead to abuses of the system if the higher-ups simply wanted to wear their red hat bands once in a while, but I think it's a risk worth taking.