Wallcat - Enjoy a new, beautiful wallpaper, every day.
Wallpaper Engine - Wallpaper Engine enables you to use live wallpapers on your Windows desktop.
Splashify - Beautiful desktop wallpapers for Mac and Windows
Video Paper - Set a video as your wallpaper.
Irvue - (previously Unsplash Wallpaper) Gorgeous wallpapers on your Mac.
Plastuer - Plastuer is a Windows application for setting GIFs, videos, and web pages as your wallpaper.