USPS Mobile for the iPhone and iPod Touch

Those of us with GPS systems already have a fairly reliable way to find a post office when we're in unfamiliar territory. However, most systems simply tell you how to get to the post office. Thanks to USPS Mobile, you can know whether that post office is open, what services they provide, and find a mailbox if you simply need to mail something.

Additionally, you can check on tracked packages/letters, and lookup zip codes for cities, and vice versa. All of the info in the app can be found on the USPS website as well, but they've done a nice job packaging it into a simple, straightforward, and free, application.

Here's a look:

USPS Mobile in the App Store.