This is a full version that is free to use but has a save size limitation of 320x320 pixels in the trial version. It has quite a few nice features for creating textures from scratch as well as modifying existing textures with different effects. It can also convert textures to quite a few different formats. There is also support for plugin tools. The weblink to download the software is Download link to Texture Maker 2.81.
PS: There's a rescale button for resizing images larger then 320x320. This is quite useful if you just want to use the program to save your work to file for most model texturing purposes. I save my textures by default to Truespace's Texture folder. This way they are ready for use with TS when texturing my models.