I don't know what kind of riding you do, but there are many options if you want to give up some gears. I converted a crappy bike into a singlespeed for urban riding with only a front brake. But then again, I'm not trying to go fast on that one. I've got another road bike with bar end shifters in the aerobars. When I'm cruising around, I can easily shift both sides with one hand. Otherwise, I agree with eddy. you can have one regular shifter and one bar end shifter
For the braking, did you want to use both brakes at the same time with one hand? If not, then you could probably mount a cyclocross for the rear on the left bar, though it'll take some funky wire routing. I haven't tried it, but I think it could work. I haven't tried it, but I'm just tossing that out there.