Helping fund development of ways to cure aging is also a thing that falls under saving the world, I think.
Interestingly, there's a great deal of overlap between this arm of the AI community and the most forward-looking longevity engineers. They go to the same conferences, seek funds from the same philanthropists, and for forth. (Aubrey de Grey, biogerontologist and now SENS Foundation CSO, even used to be an AI developer, back in the day when "AI" meant "incrementally better expert systems"). See, this, for example:
http://www.fightaging.org/archives/2010/08/artificial-intell...
The penumbra of people, funding sources, and networks surrounding the Singularity Institute and Less Wrong are much the same as the one surrounding the SENS Foundation and Methuselah Foundation - both of whom are making their year end pledge drives, by the way.