I can think of a few applications that currently aren't adequately supported
1. Play on-demand video games over the internet (e.g. OnLive). Not practical now, but both proposed versions of the NBN would support that.
2. YouTube on demand HD TV/movie channel subscriptions. This requires robust streaming capabilities, which both proposed versions of the NBN would provide.
Neither of these are essential social requirements, however. Not like, you know, hospitals and stuff.
Teleconferencing (business, medical, teaching, etc.) can already be supported over ADSL2.
I have yet to see a single essential use case that would justify the amount of expenditure proposed. The same money, were it to be invested in private hospitals or tollways, would provide a better ROI, and yield real and measurable societal benefits.