Haven't seen Inkscape here yet. I use it for almost every image editing thing I regularly do like cropping, stitching together, adding text and of course creating graphics from scratch.
Definitely GIMP .... for any kind of simple quick photoshopping once you get accustomed to GIMP, it just works for about 80 percent of everything you want to do with an image ... yes there is a bit of a learning curve but its the image editor I use the most often