Do not judge lest you be judged yourselves, For in the way you judge, you will be judged; and by your standard of measure, it shall be measured to you. Matthew 7:1-2
Be merciful, just as your Father is merciful. And do not pass judgment and you will not be judged; and do not condemn, and you shall not be condemned; pardon, and you will be pardoned. Give, and it will be given to you; good measure, pressed down, shaken together, running over, they will pour into your lap. For whatever measure you deal out ot others, it will be dealt to you in return. Luke 6:36-38
Karma is one of those words in which the origianl meaning is changing. As is true of most words that undergo a change like this, it gets misapplied a lot.
I think most Christians who use the word are referring to verses like sow what you reap and the passage above. There probably isn't anything wrong in particular with using the word, as it's meaning has changed from a strictly religious word to broader usage. I perfer the old adage "What goes around, comes around" myself.
But, in answer to your question Keith, yes we do get paid for our actions. But not in the Karmic sense. Bad/Good Karma actually means that whatever good and bad deeds one performs in this life will be visited upon one in the next life. However, there are heavenly rewards. And when we do the good works God desires of us, and love one another instead of judging each other, we do build rewards in heaven. We shouldn't think in terms of reward/punishment but rather gain/loss.
It's just important to remember that our gaining or losing heavenly rewards has nothing to do with our eternal salvation. 1 Corinthians 3:11-15.