I personally like an idea I heard a while back. Everyone earns some amounts of Karma regularly, but they can only give them to others. The karma they earn cannot count towards them. This means that if you have high karma, its because the community thinks you deserve it. If a paid worker is helping the community and earning large amounts of karma, they will have well earned it.

Karma should be earned by helping others, be it answering a question or making an app, writing a blog, writing helpful wikis. People can decide how to pass out their earned karma. It actually encourages coopetition and helpfulness.

my two cents,