The iPhone app does all of that on the go, giving you instant access to your financial information wherever you are. You can check your accounts, edit your transaction records, and see your monthly budget (so even while out shopping, you can know exactly how much money you've got to spend) as long as your iPhone has a connection. You can get alerts when something goes wrong. And security even on the mobile device is excellent -- there's a password built-in to the app, so anyone using your phone can't get immediate access to your information, and if you lose your phone, you can even disable iPhone access directly from the web app, ensuring that no one who uses your lost phone gets any sensitive information from the app.
Oh yeah -- and it's all free. Mint.com is definitely worth a look if you haven't installed it yet.