Usability 
The United States Postal Service (USPS) recently launched a mobile web site. Features include package tracking, a post office locator with information on hours and last mail pickup times and a couple of zip code search tools; one that gives the zip code for a given address and another which tells you what city a zip code is located in. For procrastinators there's also a page listing the last date to mail holiday cards and packages to various destinations.
For me the killer feature on this site would be the one that claims to return a a list of the nearest mailboxes, with mail pickup times, for a given address or zip code. This feature worked OK when searching by zip code. But whenever I tried to use it with a full street address it just took me back to the mobile USPS homepage when I clicked the Search button! There is nothing more irritating than painfully tapping in an address, street, city and state on a ten key phone keypad and than having your efforts rewarded by absolutely nothing!
Source: PhoneDog