Though I am probably in the minority, I still mail out letter to people. I know email and facebook and twitter allow for quicker interaction, but there is still something very unique about receiving a letter in the mail. The USPS has created a mobile site available from any phone that can navigate to m.usps.com. The sire only list the most important options as text links: package tracking, post office location, and two-way ZIP code look-up. I tried it on my iPhone and it looks like it can be really helpful if you track a lot of packages and need to get an update on the go.
