The Chase Currency to Go program is not a promotion. It is a service offered by Chase to buy foreign currency and charge them to your c/c as a purchase (no interest and miles)

Well, another item they sell are US Dollars travelers checks at face value. If you order more than $500, they overnight them to you for free.

You then deposit the checks into the bank account from which you pay your bill, and the charges balance out.

Your net reward: Free miles!!