Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
PaintBerri - PaintBerri is a free art site that offers an awesome oekaki community.
picinfinity - Picinfinity is an image retaining/proxy site.
slimanimation - to make stick figure or hand drawn animations
PicPicGO - Bring all of your favorite photos with mass amounts of storage space.
FurAffinity - Fur Affinity, the internet's largest online furry art community.