Karma, as it is being implemented now on the Stardock forums, is simply a popularity contest. I could, if so inclined, start a thread titled "Hooray for Big Bouncy Boobies", and garner at least a half dozen karma in one fell swoop.
There are many members of the Stardock forums who have spent countless hours of their own time through the years trying to help other members. This effort has been mostly undocumented.