probably not much, since there are already a billion other wallpaper sites out there...and probably few people who would want to advertise on them
it depends on the quality of wallpapers and how popular the topics you offer are among wallpaper-visiters. i have a solid 4 digits$/m from my wallpaper-section but i have many thousand of self made wallpapers - hence i own copyright and have nothing to fear for abuse or copyright infringement - other wallpaper sites often steal content and of course sooner or later get their site cleaned up / deleted by hosts facing a DMCA procedure. example question in your precise case: are you sure to have proper written/signed credentials and permissions for your sexy girl wallpapers to publish and market these photos from these models ?? are you the photographer ? if NOT did you obtain written permission from photographer AND from models ?? i have nearly 10k uv/d on wallpapers alone with FAR more than 10k wp downloads per day resulting in a 4 digit$/m on wallpapers re millions of other sites ... in ALL high paying high $ markets you alway have at least 1 million or MORE competing sites - if there are less sites most likely that niche has no real potential visitors and may never be worth to invest such amounts of time, efforts and $. as a result of MANY thousand $ investment in top end camera and lenses ( Carl Zeiss ) for my wallpaper production ... you earn what you invest !! if you invest MANY thousands of $ per year in production of high quality in demand wallpaper topics - then you earn a multiple of your investment. and .. may working time allocated to wp production and processing is around 1000-2000 hr per year across the past 2-3 years in addition to $ investment and thousands of kilometers in traveling by all means incl waling nature ... needless to say that in this high competition market only top SEO brings such results.
well depending on your niche, my wallpaper site for the iPhone / iPod Touch is averaging $15 / day. I started the site at the end of July.
With celebs wallpaper, 500 unique visitors, 6000 pages views, i can earn only $3, can you give some suggestions? Thank you!
Unless all your wallpaper images are public domain, my concern would be hosting adsense on pages with copyright infringements.