Material Maker - Cross-platform, procedural texture generation tool.

Filter Forge - On the surface, Filter Forge is just a Photoshop plugin, a pack of filters that generate textures...

Substance Designer - Substance Designer is a node-based non-destructive application for material authoring.

Quixel Mixer - Mixer is a PBR creation suite that uses brushes and non-destructive layering to generate all types of maps.

Substance 3D Painter - Substance 3D Painter has the tools you need to texture your 3D assets, from advanced brushes to Smart Materials that automatically adapt to your model. Breathe life into your art.

TextureLab - Free, Cross-Platform, GPU-Accelerated Procedural Texture Generator.