you could look into coaster brakes. That's the way I'd go, if I were captured by the crime boss and forced to make a bike with no cables. You could coast, rail corners, bomb hills...I guess that's not appealing to fixie guys in the street, but those are high up on my bike fun goals.
I'm not sure if there are coaster brakes that look any different than they used to, but you could probably paint it the same color as your frame and make it seem smaller.
Some frames have internal cable routing. That's a nice pain in the ass that'll never go away.
Aesthetically, I understand the "simple is beautiful" thing with fixed gear bikes, but the frames some people choose are far more vomit-inducing than a cable would be: the 70s Peugeot's are the ones that kill me around Seattle. Long wheelbases, and those god damn forks that turn chrome halfway down and bend like three inches? Killing me!
I like any bike that the owner likes, but I can't always see them being good for me. Last page, bandagekills with this one:
You could take off the front brake for your simplicity needs, and it would still be acceptable to me because it could rail turns and bomb hills. But you're probably wanting to get rid of the back brake, because of all that pesky brake cabling, and now I'm afraid to bomb hills or rail turns on it.
there could be some weird internal drum coaster brakes out there...
the bmx street kids all ride brakeless, by the way. freewheel and all...sometimes freecoaster and all...insane.