1)   Genetica 2.0
Genetica 2 is a seamless texture editor with over 500 texture presets and automatic seamlessness. Among hundreds of new features are a new Substance Lab, a new Weather Lab, a new Cut & Tile Lab, and much, much more. Also comes in Pro edition.

 2)   Seamless Texture Generator 1.361
Seamless Texture Generator is a tool for creating high-quality seamlessly tileable images from photographs quickly and easily. STG will save you hours of work. It makes most textures seamless with a single click!

 3)   Wood Workshop 1.0
The Wood Workshop is a free seamless texture editor that specializes in the creation of seamless wood textures. It comes with a collection of over 100 preset wood textures, all perfectly seamless and ready to go at resolutions up to 3000 x 3000!