Isometric Game Art Pack - Extensive library of game art for indie devs
Canva - Canva is a graphic-design platform with a drag-and-drop interface to create print or visual content while providing templates, images, and fonts. Canva makes graphic design more straightforward and accessible regardless of skill level.
Sketch This - Daily drawing challenges
PicMonkey - PicMonkey is a feature-rich online photo editor that works right in your browser; no downloads...
IsometricSass - Make isometric 2D objects without Javascript
Piktochart - Piktochart for Business Storytelling