I took several of my favorite wallpapers and "re-formatted" them for my z... Feel free to grap as many as you like from here:
30 Zaurus Wallpapers
I discovered that the best settings are 640x480, 256 colors, and indexed - not RGB.
These wallpapers were "made" with landscape in mind...
Also, these are NOT my originals, so if any of the original artists prefer I not post them, I will be glad to remove them - just ask. Most are Linux / anime / etc.