Most people don't live on Wall Street; even bankers don't always have ready access to their work materials. For all of these people, apps like XE Currency are a great boon. Using XE's time-tested window into global trade, the app tracks both current and historical values of currencies. You can follow multiple currencies at a time as they update every 60 seconds, and even store these values for offline perusal.
XE Currency is tremendously useful any time there's currency management to do.