Chimps in Japan have been seen helping their companions out, purely on the basis of need. They would hand tools over to chimps in a nearby pen; and most notably this was most likely to happen if the chimp really needed the tool and requested it, rather than if they just wanted it to play with. This shows that chimps care about the welfare of their fellows and will assist them even if there is nothing to be gained themselves.
This helping is not just reserved for other chimps too – in a previous study by Warneken, chimps were also witnessed helping humans in a similar task and handing a stick to them on request. Videos of both of these experiments can be found below.
Chimp helps human- scroll down the page, and play the first video in the list.
Sources:
Yamamoto, S., Humle, T.,Tanaka, M. (2009)
Chimpanzees Help Each Other upon Request
PLoS ONE, 4(10): e7416
Warneken, F., Hare, B., Melis, A. P., Hanus, D., Tomasello, M.
Spontaneous Altruism by Chimpanzees and Young Children
PLoS Biol 5(7): e184