Website: wallbase.ccI have been an ardent follower of wallbase.cc. The site's got some awesome design and the wallpapers there easily transform your everyday average desktop experience into awesomeness!
So when I stumbled onto the Windows Phone app of wallbase, I was expecting something that would be fairly basic. I thought that it would let you see the categories, top images and let you do some basic stuff. But when I used the app I was totally surprised. The design and the functionality provided really knocked the socks off me. The app looked awesome, was very responsive and fast, heck, it worked absolutely fine even on my 2G connection. Then there was the downloading of images which was awesome-start a download and go back to main screen to browse the images. Depending on the speed the download would finish and you get a popup. No more being blocked to the download screen or anything. It kind of defined what a smartphone app should be.
Then couple of months ago I got hold of an android phone. So just to check it out, I got the droid version of the app. And for a simple app it provides enough functionality for general use. It's again as easy to navigate as the Windows Phone app and it's fast. Only think I have against it is that the margins between columns of images are not uniform so it feels a bit weird to me. But it does have more features since the Windows Phone application is limited thanks to WP's sparten feature set.
Overall I would say if you want some totally awesome wallpapers, give wallbase a try and you won't be disappointed.