A missclick made me lost all what I wrote before creating this topic, so I will be quick:
Yesterday I bought this software:
For just 3 dollars. It's a key for Steam, so you will need a free Steam account to use it.
Here is a video:
Not sure how professional it is, but you can get a pretty good and quick result, even if you know nothing about normals and stuff. You only need a diffuse image, or you can even import other maps to work with it.
You have sliders for better adjustments, a 3D preview to see what those maps do in real time and you can also import your objects for the preview.
This software will create the next maps: diffuse (if you modified it), normal, height, specular, gloss, self illumination, reflections and ambient occlusion.
I just wanted to make you know about this offer. It ends in 10 days, so you have time to think if you will need it or not.
You have free alternatives, yes, but not all of those have sliders and a real time preview.