Currently changing video options can break the game:
viewtopic.php?f=47&t=71557
This could be resolved by non-committal option changes until they're verified by the user on their end, this would prevent permanent damage. (It's just like changing your screen res).
Similar to options, some ingame actions should also have a toggle for warning. Ender's client does this for dropping items, this would prevent accidental miss-clicks resulting in you dropping your key into the river or something or a bucket.