GIPHY Create - Create animated GIFs from videos (by Giphy)
Placemat - Pretty nice placeholder images.
Instagiffer - Create GIFs from anything!
Fill Murray - Custom-sized placeholder images of Bill Murray
Giffing Tool - Giffing Tool is simply put: The fastest creator of high quality captioned GIFs available.
PlaceKitten - Dead-easy placeholder images. Of kittens.