To the OP: Get some brake levers (yes, two, so you can get a flip flop hub) and two brakes to go with them. I agree with whoever said that they're practically worth it for the ability to ride on the brake hoods.
I have to admit that I personally *never* used the freewheel on my flip-flop hub. But when I eventually sold that fixie on craigslist (had to reduce my stable to 3 bikes due to moving to a smaller place :'(), I think I got a lot more interest and a higher price because it had two brakes and a flip-flop hub.
I had a previous fixie with only one brake, and I liked the two-brake version a lot better because of the hoods AND because the feeling of braking the rear wheel on a fixie is weirdly cool.
Seems like the consensus on this thread is:
* Get the brake(s). You'll be glad you have 'em when you occasionally NEED them.
* Having brakes available won't hinder you in using a fixie to strengthen your legs and improve your cadence
* The only reason not to have brakes is for style.