Textureking TextureKing has a collection of nice textures to give effects to your photos.
Paint.net Paint.Net is a beautiful photo editor with which a lot is possible. This editor is often mentioned as a replacement for Photoshop or Gimp. There are many free plugins available through their website.
Krita Krita is a digital painting program that is also very rewarding for photo retouching.
Google Nik Collection The Google NIK Collection is a collection of 7 programs for perfect adjustments to your photos. A program that you must have!
Gimp Gimp is the photo editor par excellence if you want to edit a photo and have no Photoshop. When you download the installation package, it automatically installs the 32 or 64 bit version, depending on your system.
Abstract Curves Abstract Curves is software to generate beautiful graphic images through two generators. The image can be influenced with many parameters. A download is available!