NeoTextureEdit is an open source (GNU LGPL v. 3) easy to use graph-based procedural seamless texture editor. Using continuous basis functions it can generate arbitrary resolution images without quality degradation.
Texture Studio is all you need to produce professional quality textures for use in games and tiled backgrounds. Texture Studio includes a set of integrated tools, all extremely useful for creating high quality seamless textures.Discontinued
Alternative download available here https://sites.google.com/site/gibbagobba/downloads