Yeah, that one is really good too, it would be a hard choice between that or all known mathmatics. The languages would definately come in very handy.
I’m voting for autistic math ability, minus the autism, too.
That, or maybe Master Propaganda Skills. Y’know, so I could bend the masses to my will.
A musical instrument, or really learning how to fight.
[QUOTE]
If you could upload one program into your brain… {/QUOTE]
…it would train me never to be overweight again.
Hell yeah. And some form of grammer check.
I’m crap at both. Not that I wasn’t taught it, it just didn’t stick.
I guess my brain is music based and not word based. 
Forget “programs.”
The timbre, volume, range, depth and flexibility of an electronic synthesizer modulated mentally and expressed through my vocal cords.
The ultimate mimic.
All medical knowledge.
Ehh…
It’s really hard to say, but I’ll to go with the ability to write a good paper.
I’d like an emulator program that allows my brain to imitate computer functions. It wouldn’t be as good as a real computer brain implant, but since those don’t exist yet, I come out ahead.
How about Mathematica: It could do computations for you (even calculus). Of course, it won’t convey understanding.
I’d like something that would allow me to get something like BodyBoss. Where I could modify and control various aspects of my body.
Let’s say I lose a hand. Send out the cell brigade to rebuild it.
Oops, getting a little fat. Send them out to kill the fat cells I don’t want.
Darn, not strong enough. Send em out to beef up my biceps.
Memory’s not good enough. In they go to build upgrade that part of my brain.
Damn! My eyes ain’t as good as they used to be. In they go to rebuild them.
A god damn flu bug trying to get into my body! Smash it.
Want to impress/freak out a girl? Swarm them cells to my skin and make her name appear.
Holy crap, there’s goes my hair! Quick, build new folicles. And get rid of all those folicles on my back and in my ear please.
… Since I could go on and on I guess I’ll stop here. But man-o-man would I love that.
You know, it seems the further we get physically from your OP, the further we get mentally as well.
If it was something more in line with your OP, well then I guess it would be the ability to speak, read and write Japanese. Especially since I really should have taken that instead of French in High School. I mean really! I live in Hawaii. What was I thinking?
Blatently Kung-fu.
Do I get the certificate and licensure to go along with it? Then I’d like to become a nurse-practitioner, thank you. Neonatology will do.
If not…well…frell it. I guess the download will make it easier to go to school anyway, so I’ll still go ahead and take it!
It would probably crash your brain!
I’d go with languages. Mandarin would be useful along with Arabic. Or, a program that would allow for a photographic memory. I could learn whatever I needed afterwards.
Uh, the OP specifically stated that only one language would be the limit of the download. Speaking all languages would make you extremely valuable and unique and would be worth using your one download on. Speaking just one additional language would be a waste, unless you have a really good reason for it. There’s plenty of multi-lingual people out there already. You’d just be average.
Compare being bi-lingual to having complete medical knowledge, knowledge of any number of high paying fields such as nuclear physics. Learning computer programing languages would be tempting, but there’s always the difficult choice of which one to pick. You don’t want your new skill to become obsolete in a few years. Tax laws especially would be useless after one year. As would legal precedent. I’d say it would be more valuable to pick something that is more static: Math or science.
If you can do trigonometry in your head, you could get a cool job at NASA or a cushy job in academia.
PowerPoint. That way I could help people by curing their insomnia.
Maths; specifically calculus. Other things such as the ability to read music would be more practical, but my inability to perform (or even fully comprehend) calculus is I think the thing that annoys me most.
Is it too crass to say “eBay”? So I’d know every auction on it, the current bid, and the ending time? That would be fun and lucrative.
Anti-virus.