Izbushka allows you to organise your collection by categories. No need to convert images to match your desktop dimensions. The program fits each image automatically using very smooth resising algorithms.
Adding new wallpapers is very simple: just drag an image with your mouse and drop it into Izbushka.
The program can constantly monitor specific folders for new images. It will use new images as soon as you save them there. No need to do anything else. Just save an image and Izbushka will use it.