google, deviantart, wincustomize, there are hundereds of wallpaper sites on the internet. and due to the resolution of the phone any computer WB will have an option for a size for the phone.
anything larger than 1200 in each size is fine for the GN.
personally i get almost all my wallpapers from deviant art and other wallpaper sites. and some here from the post your homescreen topics.
right now in my phone i have 85 wallpapers, maybe 10 of them i got here. rest were google and deviant art.
Nexus 4 - AOKP Android 4.2.2
Asus EEE Pad Transformer w/ Keyboard - ICS 4.04 | Asus Google Nexus 7 - JB 4.1
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