According to an article in the Dallas Morning News:
Boyd said that because of Frisco's growth, the postal service ran out of the plus-four-digit numbers that go after the ZIP Code in the 75034 area of Frisco. The plus-four-digit codes help the post office's automated equipment process and deliver the mail to the correct address.So who is the lucky owner of the .com domain for the new zip code, 75033? According to whois, it's Chen Caidong, in Beijing, and his email address contains the word "domainreseller". Congratulations Chen, although I imagine you bought the domain for other reasons.
Anyways, just goes to show how numeric domains have multiple uses and sources of value across languages and continents.