ZIP+4 codes

[pne]

A poll mostly for those who live in the United States:

Edit to clarify: "do you use it" means "do you write the ZIP+4 code on the envelope" rather than "do you use any form of ZIP code". (I take it for granted that most people write at least the basic ZIP code.)

[Poll #577139]

I'm curious, because I tend to try to find out ZIP+4 codes when I write to people in the States, perhaps for geek value; however, I've found it extremely rare for people to quote ZIP+4 codes in their addresses.