FreshBackMac - Fresh backgrounds for your Mac from multiple sources
Wallcat - Enjoy a new, beautiful wallpaper, every day.
Multiple.js - Sharing background across multiple elements using CSS
Splashify - Beautiful desktop wallpapers for Mac and Windows
Is This Big Enough? - Request & receive the right size images from clients
Irvue - (previously Unsplash Wallpaper) Gorgeous wallpapers on your Mac.