1) PixBuilder Studio: http://www.wnsoft.com/it/pixbuilder/
It's very nice and similar, but very light, to Photoshop.
That is the Free edition. I don't know about the license.
2) Color Cop: http://colorcop.net/
It' a color picker
3) and something very very light and simple like Paint of Windows XP.
Is it possible?