For NO PARTICULAR REASON, we just wanted to remind everyone that even if you don't have a US credit card, Apple has helpfully provided a knowledge base article on how to create and use US App Store accounts. With these accounts, you can still download and use apps (and redeem promo codes).
The process involves making sure you're not already logged in with another account, then choosing App Store from the menu, downloading a free app, choosing "none" for the payment type, and responding to the confirmation menu.
Downside is it requires you to download apps via iTunes -- for now. iPhone 3.0 will let you manage multiple accounts on-device.