Dr. Don's favorite:
Personal Assistant Premium by Pageonce: Like Mint, this application tracks all your accounts in one place. Unlike Mint, it allows you to enroll and add accounts via the iPhone. The initial account setup and data retrieval was lightning-fast.
This application also allows you to track other activity, such as your Amazon.com account, cell phone usage and real-time updates on flights. The interface is strong and very simple to use. The app was conceived as a personal assistant, so it can track just about whatever you can think of that needs to be tracked.
Be aware there are two versions of this application -- the free one with less functionality and ads on the bottom and a paid version that has more functionality and no ads. The website explains the different features in each version. Decide if you need all the extra information before you hit the "install" button. That being said, Personal Assistant may be my favorite app to date.