Material Maker - Cross-platform, procedural texture generation tool.
Substance Designer - Substance Designer is a node-based non-destructive application for material authoring.
TextureLab - Free, Cross-Platform, GPU-Accelerated Procedural Texture Generator.
PixaFlux - PixaFlux is a node based image processing application.
JSplacement - JSplacement is a cross-platform pseudo-random 8K displacement map generator written in HTML and JS.
PixPlant - A complete solution for repeating textures and 3D maps. Save a lot of texturing time with PixPlant!