Brain, back, one eye, penis. Why the hell not? ;)
Oh, and the AI in DXHR. Then, all would be beyond awesome.

My brain, especially the part which needs 7-8 hours of sleep per day. Then maybe remove the need to eat to stay alive.

I want a brain augment to give me godlike powers.

I'd get my weiner augmented. Then I could get a job in porn. Hmm hmm, yeah. And I could get paid lots of money to do it with hot chicks! Yeah! Hmm hmm, heh.

/Beavis

A skull gun, obviously.

A bigger penis, obviously.

I was trying to resist this obvious answer, but yeah, I'd augment that first. Then maybe go for super strength. Eyes that can shift frequencies at will would give me low light and x-ray vision at will. A brain implant that can stimulate any kind of high would save me tons of beer money.

I want one of those breathing enhancers, Someone was talking about it in the limb clinic :o

This. :)
You're probably right, but out of curiosity, a friend of mine has some kind of "augmentation" which is also "pure machine" and has a degree of tactile feeling. Get this: one of his legs is actually a simple prosthetic replacement from the knee down (he was born without that part of his limb). He's used to walking with that for years and he swears he actually feels the ground very well (ie. he always knows when he steps on a different material or when he steps on a rock). Of course, he feels it from the knee, and he doesn't have the direct input from the touch of the foot itself, but he's so used to the prosthesis he can feel stuff you wouldn't imagine.

Your mom.

After talking with my girlfriend, I would change my selected augments to be my tongue.

I gotta be honest, I would totally pull a Johnny Mnemonic and want a cranium implanted storage device for info, with data port installed. Imagine actually being an information transporter, you could make a killing in the business sector.

So a pack mule for data?

That, or a corporate espionage agent. Holding the most vital information of the largest corporations in the world..at the nerve endings of your brain.. -Insert Evil Laugh Here-

So...if I were to, say, whack you in the back of the head with a crowbar or throw some magnets at you, how bad would that be for you?