Lafleurs Guy,
here's a link to the GVT (goals-versus-threshold) stat that MathMan was mentioning though it hasn't had an update since March 7th for some reason.
There's also a primer about what it is and how it is calculated[/url] (clicking next column at the bottom of the article will bring you to parts II and then III). If you have some spare time and want to check it out that would be a decent start.
When I started reading about microstats it was the easiest stat for me to understand and it factors in offensive and defensive value to a degree making it somewhat holistic. It's main weak points are it doesn't account for quality of opposition where on the ice a player starts their shifts but it's a good first stat.
I wouldn't be comparing the value of goaltenders to the value of skaters in using it though - goaltenders tend to be rated highly across the board and it's the marginal difference between them that is more important.
It's a good stepping stone into the hockey microstat world though if you're inclined to want to read up more about it.