Listening to a local radio station the other day, I heard the DJ asking for listeners to send support money for Hurricane Katrina relief. His reason as to why we should donate money was to "get good karma"; in other words, if we do something nice for another person, then something nice will happen to us.
While this particular usage of "karma" is very common and relatively harmless, I still do not find it very satisfying intellectually. At best it is a vague sort of sentimentilism. At worse, it is the ethical egoism (i.e. we should be nice to others because it ultimately benefits us) of Ayn Rand resurrected.
The Christian faith has another reason as to why we should help others in times of need: we help others out of love for God. Our helping of others is an offering of worship and praise to God. In addition, it is an act of obedience to our heavenly Father. And finally, we help others out of love for them - as people made in the image of God.
I am happy if anyone wants to send aid to people in need. As far as I am concerned they can do it in the name Dr. Spock and the Starship Enterprise. But in my judgment it is the Christian faith and tradition which offers the most fully satisfying and consistent rationale for acts of charity.