The office I work in has a casual dress code, which makes Casual Friday unnecessary. Much of the time, I'll wear jeans and a hawaiian shirt. It's easy and comfortable, but hardly impresses anyone (except, perhaps, the sheer quantity of hawaiian shirts I have).
A few weeks ago, Bill, leader of the Usual Suspects, clued me into a great sale at Macy's, and I picked up a weeks worth of shirts and ties. I don't have call to get dressed up very often, but I figured having a nice selection on hand wasn't a bad idea. And it was a great sale.