A lot of places use IB (including certain Australian schools), where you have to do six subjects. The catch is that five of them have to be from different disciplines (one English, one Maths, one Science, one language and one humanities), with a sixth that is up to personal preference (can be another science or humanities generally). In year 12 you'll also pick three of these subjects to do "Higher Level" in, so a sample IB course would be HL English, SL Maths, SL Physics, HL Latin, HL History, and SL Economics. In the process they also have to write an Extended Essay (3000 words) and do this pseudo-Philosophy course called Theory of Knowledge. Generally speaking SL is about lower VCE level (eg. SL Maths is roughly Methods) whereas HL is upper VCE level/lower Uni level (HL Maths combines something like Spesh and 1st year Uni Maths).
US uses SAT primarily (I think?), which is basically a series of three tests which you can't "study" for (kind of like the UMAT). Each is marked out of 800, and the three tests are on Maths, English and Writing.