I like the concept of using multi-sig to do legal tax planning.

http://youtu.be/7UEjxH7C95o?t=1h10m15s

Like Amazon, Apple, Google, etc having multi-location tax planning to move cash to the most efficient locations.

One entity or legal partnership spread around the world with multi-jurisdiction rights to apply local tax rules, eg tax havens, giving wallet access to each entity, but with built-in safety features.

That is such a cool and potentially killer feature of crypto. Especially with DRKs anonymity layer on top.

I'll have to do some digging around on the various tax codes and rules to figure out whats what.