Isometric Love - Cute isometric objects for designers
Isometric Game Art Pack - Extensive library of game art for indie devs
Isometric - Create beautiful, abstract works of art & optical illusions
Indie Boost - A video game discovery software used by Publishers, Press, YouTubers, and Streamers.
Sketch Isometric Plugin - Generate isometric views from artboards and rectangles
OpenGameArt.org - A site dedicated to sharing artwork & other assets for game development.