My cousin shared this story from India -- and I am passing it on because I liked it a lot.

Once Krishna and Arjuna were walking towards a village. Arjuna was pestering Krishna, asking him why Karna should be considered a role model for all Danas (donations) and not himself. Krishna, wanting to teach him a lesson snapped his fingers. The mountains beside the path they were walking on turned into gold. Krishna said "Arjuna, distribute these two mountains of gold among the villagers, but you must donate every last bit of gold". Arjuna went into the village, and proclaimed he was going to donate gold to every villager, and asked them to gather near the mountain. The villagers sang his praises and Arjuna walked towards the mountain with a huffed up chest. For two days and two continuous nights Arjuna shoveled gold from the mountain and donated to each villager. The mountains did not diminish in their slightest.

Most villagers came back and stood in queue within minutes. After a while, Arjuna, started feeling exhausted, but not ready to let go of his ego just yet, told Krishna he couldn't go on any longer without rest. Krishna called Karna. "You must donate every last bit of this mountain, Karna" he told him. Karna called two villagers. "You see those two mountains?" Karna asked, "those two mountains of gold are yours to do with as you please" he said, and walked away.

Arjuna sat dumbfounded. Why hadn't this thought occurred to him? Krishna smiled mischievously and told him "Arjuna, subconsciously, you yourself were attracted to the gold, you regretfully gave it away to each villager, giving them what you thought was a generous amount. Thus the size of your donation to each villager depended only on your imagination. Karna holds no such reservations. Look at him walking away after giving away a fortune, he doesn't expect people to sing his praises, he doesn't even care if people talk good or bad about him behind his back. That is the sign of a man already on the path of enlightenment".

http://www.quora.com/What-are-some-lesser-known-stories-about-Karna