Placemat - Pretty nice placeholder images.
Fliqlo Screensaver - A screensaver that displays the time using a flip clock.
PlaceKitten - Dead-easy placeholder images. Of kittens.
Clock.saver - A simple clock screensaver based on Braun watches ⌚
placeholder.pics - Lightest way to include placeholder images in your design
Aerial - A beautiful aerial screensaver for your Mac