I found Gimp to be one of the most versatile tools on the market. It works like Photoshop, it’s very light and it’s available on across different operating system. The fact that is free is just the cherry on top. People are in general very hard to convinced to work with this tool. I believe it’s a similar experience like going to Linux from Windows or Using Open Office instead of Ms Office.
The future is bright for this tool because in the next version ( 2.8 ) the developers will finish : Single Window Mode. Until then ( the end of the year ) the following tips might help some of you work with this tool and maybe start understand that this is a true replacement for the proprietary software named Photoshop.