Snappr is a little utility that lives on the menu bar on OS X. Do you think that changing your wallpaper is a daunting task? Then Snappr is made for you, as it automatically changes the wallpaper of your Mac from the images posted on the subreddits you have chosen.
It only uses images with the appropriate resolution (and it’s fully compatible with Retina Macs) so you don’t end up with a pixelated background in a high-resolution screen.
In addition, it avoids repeating the same image in order to have a fresh work environment.