Slight hijack because I don’t know the US usage but:
NZ: At the moment
UK: At the minute
Well, I’m British, have ‘taken’ an awful lot of tests in my life and have never ever heard it said.
Yes, it’s a British term but perhaps getting a little antiquainted. No doubt they still say it at Oxford.
For another colonial perspective on what one does to exams: in South African English we say “write an exam” and I don’t think I have ever heard people use “sit”. We even use it without explicitly mentioning the “exam”: for example, “When do you write Algebra?” and “I’m writing on Tuesday,” although that type of use may be specific to students.
Incidentally, preparing the question paper we call “setting the exam”, and assessing the results we call “marking”. I think this is the same as UK usage.
I think the other form is a little archaic. You find it in Agatha Christie novels and others of that ilk.
Ah! well there we go. Very few of us live in Edwardian times 
It’s is well over a month since I even slapped a servant, never mind murdering a footman.
It might be akin to us expecting all Americans to say “yer darn tootin’” to mean “yes, you are correct”
Edited to add:
and I just noticed your username, perfect for an Agatha Christie reference!
UK - “I’m going to hospital” or “I’m going into hospital” means I’m being admitted to hospital. “I’m going to the hospital” means I’m going to the hospital building but not as a patient.
Likewise with school, possibly other institiutions as well. Going to school means you’re a pupil. Going to the school could mean anything except that you’re going there as a pupil.
Or UK: BP have spilt some oil. Spilt, spelt, dreamt are all valid UK forms.
I agree (and I also understand that’t just the way things are), but to me, it sounds like a list being recited. i.e:
UK: One hundred and twelve = 112
US: One hundred twelve = 100,12
I think I was already familiar with most of the usage differences noted so far, but one that I only realised recently is “roommate” - you see it a lot on predominantly American boards, and I always assumed it was because there are lots of university/college students posting. Because to me, a roommate is someone who shares a bedroom with you (but not your bed), like people often do at college.
In fact, it seems that in the US “roommate” means someone who shares accommodation with you, not necessarily a bedroom. So it applies to a lot of people who are past college age. We would use “housemate” or “flatmate” for that.
“Knock up” meaning prepare is certainly quite common… it has that quasi-cockney sound to it that folks like Jamie Oliver have popularised. Been around as long as I can remember though.
The discussion around “Cheers” is very astute so far - in Chicago, I’ve continued to use it as I did in the UK: for thanks, drinks, goodbye, email signoff the whole lot. It caused confusion, but not for long - but I certainly do now have a few college-types in my office that have adopted it in their speech and emails.
Another one not using the word “piss” but riffing on a theme is:
US: Taking a Mickey (well, close to slipping a mickey)
UK: Taking the Mickey (again, ridiculing someone, evidently a popular passtime the UK)
Not that anyone in the US would say Taking a Mickey, but I’ve had to completely scratch the phrase from my vocabulary because I have found the UK meaning is alien over here.
ooh, yeah, when people reference mickeys in the US, in my experience, it is only ever as the phrase slip 'em a mickey.
My Scottish uncle, working in Canada, was asked to place a warning sign at work near an area where one might trip. His sign read:
“Mind your step.”
Much hilarity ensued. It would always be “Watch your step” here, as he was reminded for the rest of his career.
Another one is the use of nearly and almost.
US - We almost made it!
UK - We nearly made it!
Canadian here. I say, “have an exam”, or “have got an exam”. Examples: “I have a calculus exam next week, so I’m busy until then.” “I’ve got an exam on Thursday.”
But we tend to say “taking” for the whole course: “I’m taking Calculus 101 this semester” or “I think I’ll take that Mechanical Ventilation course in February if I can afford it.”
I’m not sure what we say for preparing the exam, other than “preparing it”. But I also say “marks” instead of “grades”, as in “I wanted to go to university, but I didn’t have the marks for the engineering I wanted, so I went to college for electronics instead.” I think this helps to separate the things we are measured by in school from the names of the different levels of school (“she’s a grade 9 student”, “how were your marks in grade 10?”). A teacher might say something like, “I just got the grade 12 marks for the last test, and I’ll hand them out tomorrow.”
Is there some alternate meaning of “mind” in the US that would explain a career’s worth of hilarity, or are they just *really *easily amused?
We’d say almost as much as we’d say nearly.
As a Texan, I would assume the same.
also
UK: He/She is on line.
US: He/She is in line.
I never quite understood that. “On line” is what you are right this moment. “in line” is what you are when you are “in” a line of people.
In the UK you read a subject at university.
In the US you study a subject at college.
I’ve never heard any British person say that someone standing in a queue was waiting “on line”. We very seldom (and by we I don’t mean me) would even say “in line”. We call them queues. I can’t imagine where you’re all getting this from. There are some other hilarious misconceptions in this thread, but I can’t be bothered to read back and find them.
Kiwi in the US here … probably much the same as UK
Politicians in an election …
US: Run for congress or whatever
NZ / UK: Stand for parliament or whatever
In New Zealand it’s half past but since we tend to conserve bandwidth down there we pronounce it more like:
Hupast six.
I remember in my childhood when I suddenly realised that the first part of that word was half. 