With the 1.4 release, we have integrated 2 extensions in order to make WallBot more useful:
Activate it from Safari’s preferences and when navigating trough unsplash.com, when hoover mouse over an image, you will have an extra “Set as wallpaper” button that will set that image as wallpaper at full resolution.
Notification Center Extension
See awesome images in notification center and set them as wallpapers if you like. You can manually change the images category and change displaying image.