PNGEgg - PNGEgg is a library of transparent sticker png images for designers.
Img.vision - Image hosting & video hosting for eCommerce sellers
Free Icons PNG - Daily updated free icons and png images for your projects. All images use to free for personal projects.
UploadHouse - Thumbnail and resize your photos and images
Freepik - More than a million free vectors, PSD, photos and free icons. Exclusive freebies and all graphic resources that you need for your projects
ImageVenue - ImageVenue is a great online hosting service that allows uploading pictures for showing creative works with a simple-to-use technique.