Textures.com - Textures.com is a website that offers digital pictures of all sorts of materials.
Img.vision - Image hosting & video hosting for eCommerce sellers
Poly Haven - Poly Haven (formerly known as Texture Haven) is an online website where you will find scanned textures without any cost and that are of high quality.
UploadHouse - Thumbnail and resize your photos and images
Poliigon - A library of materials, and HDR's for artists including free textures that want photorealism.
ImageVenue - ImageVenue is a great online hosting service that allows uploading pictures for showing creative works with a simple-to-use technique.