Large currency denominations COMMONLY in use
I've often noticed that Europeans don't seem uncomfortable using much larger denominations than do Americans. When I go to an ATM in Europe and take out a couple hundred Euro it is common to receive 2 100 Euro bills, or maybe 50s. When I go to use them no one blinks an eye.
In the US, ATMs almost never give out anything larger than a twenty, and when I have a 50 or 100 dollar bill for some reason I have to convince a store to take it.
Just an interesting cultural difference.