I have several villages that have been running a while now, so I ring the gong once every day. Effects I've seen (that I remember):
Grants Health
Grants Food (usually 500)
Grants Technology
Grants Life (all eligible women pregnant)
Grants Wisdom
Grants Vision
Grants Youth
Grants Luck
Takes Away Health
Takes Away Food (lost everything once, over a million food points)
Takes Away Technology (lost over 4 million tech points one time)
Takes Away Life (at least one dies)
Takes Away Wisdom
Takes Away Youth

There are more I think, but that's what I remember right now. For every good one there is an opposite negative one. More often I get the good, but when they're bad, they can be VERY bad, as opposed to when they're good, they only seem to be "okay"--nothing extraordinary. It would be nice to see some extraordinary good, that doubles tech points or food, for example, to match the severely negative ones.

What I find amusing is that every day when I first open VV2 up, all the villagers (except kids) are either in the ocean, looking out to sea, or in the pond, looking the other way. Usually divided about half and half. Are they amphibious? :-)