These are all my own images, that I cropped and resized for the G1. I know that people have thought my images came with it. You can check out my set of wallpapers
and see if there are any you like.
This is the one I use. It seems to work really well, with the horizon line.
Right now, there are 12 images, please feel free to try them out. They have all been released under creative commons.