What is a major social problem?
Any software that's used in such a way that more than one person is impacted by its use, has a social impact, and possibly solves a social problem (or could cause one).
When the chief of the tribe only had 30 people in his tribe, it was easy to keep tabs on them all. Nowadays, a tribe chief has on the order of 300 million peoples to keep tabs on, not counting the other tribes. Then software such as PRISM solves the social problem of helping the tribe chief keep tabs on his people.
