€ = shift-option 2 on a Mac (US keyboard layout, that is).
Only semi-intuitive, that one. Nothing two-ish (or @-ish) about the euro, but it’s in a region of the keyboard where currency symbols in general exist ($ is shift-4; ¢ is option-4; £, the “other pound key”, is option-3 instead of shift-3 which is #; but lest too much consistent assert itself, ¥ is option-y and not in the “currency group” with the others).