My checking account is at a small credit union so I always call them to let them know I'll be using my card in ATMs overseas - I would imagine they're a bit faster on the trigger to disable a card for suspected fraud than BoA, Chase, Citi, etc because it's harder for to absorb fraud than it is for the big boys. Haven't had my card disabled yet.

Citi and CapOne have online forms you can fill out, takes 30 seconds. And AmEx says you don't need to call.

CapOne's fraud department seems bipolar. Once I booked a hotel in London (without submitting travel notice since the actual trip was months away), and got a call from their fraud department seconds after I clicked the button to book it - seems the $1 (or I guess the £1) authorization to make sure the card is valid triggered their fraud alert system. But other random online purchases I've made in foreign countries don't trigger it.