Think about usability - when a user enters your site, where do they look? How long are they going to take to get to what they want to on the site?
I'm quite tired at the mo, and when I looked at the index page, I couldn't really be bothered to read the blurb at the top, nor your message on this thread (nothing against you! just tired!), and so when I got on to your site, I hadn't really got a clue what it was for. My focus then went to the navbar at the top, and sure, it quickly made me realise that this site was for wallpaper.
I know it sounds silly, but how about making the site exude wallpaper from the home page onwards. Give some wallpaper images on this page - tempt people to click through to more. Also, make the blurb on the home page more 'bitesize' - either reduce the width; make it look more interesting; or get rid of it altogether - is it really necessary?
Anyway, site does look nice, I'm just being overly critical for this review!