Startup Stash - A curated directory of 400 resources & tools for startups
Placemat - Pretty nice placeholder images.
Startup Buffer - Startup Buffer is a premium startup directory for emerging startups all around the world.
PlaceKitten - Dead-easy placeholder images. Of kittens.
Content Marketing Stack - A curated directory of content marketing resources
placeholder.pics - Lightest way to include placeholder images in your design