In addition to the games, there are several extra items for fans that were released alongside or for the promotion of the Zone of the Enders series, such as soundtracks and artbooks including interviews and such. Though hard to find nowadays outside of auctions, listed below are some official Zone of the Enders and related goods.

ZONE OF THE ENDERS

Zone of the Enders Original Soundtrack
Zone of the Enders Soundtrack Single: "KISS ME SUNLIGHTS"
Zone of the Enders Premium Package
Zone of the Enders KONAMI Official Guides
Zone of the Enders and Shadow of Memories Demo
Zone of the Enders Perfect Guide
Zone of the Enders Promotional Poster

ANUBIS: ZONE OF THE ENDERS

ANUBIS: Zone of the Enders Original Soundtrack
ANUBIS: Zone of the Enders Soundtrack Single: "BEYOND THE BOUNDS"
ANUBIS: Zone of the Enders Premium Package
ANUBIS: Zone of the Enders Trial Edition
ANUBIS: Zone of the Enders KONAMI Official Guides
ANUBIS: Zone of the Enders Special Edition [Limited Edition]
ANUBIS: Zone of the Enders "Anubis" Model
ANUBIS: Zone of the Enders Cellphone Strap
The Visual Works of ANUBIS

ZONE OF THE ENDERS: 2173 TESTAMENT

Zone of the Enders: 2173 Testament KONAMI Official Guide

ZONE OF THE ENDERS: 2167 IDOLO

Zone of the Enders: 2167 Idolo Original Soundtrack
Zone of the Enders: 2167 Idolo Promotional Poster

ZONE OF THE ENDERS: DOLORES,I

Zone of the Enders: Dolores,i Original Score Volume 1
Zone of the Enders: Dolores,i Original Score Volume 2
Zone of the Enders: Dolores,i Soundtrack Single: LAZY
Zone of the Enders: Dolores,i Soundtrack Single: Ring on the World
Zone of the Enders: Dolores,i Trading Card Collection
Zone of the Enders: Dolores,i Mousepad
Zone of the Enders: Dolores,i Telephone Card

Thanks to Snatcher from JunkerHQ for several of the images!