Family trusts, forming a corporation, passing on a business before death, etc.
A few ways to hopefully not pay the insane taxes.
In my experience, almost every "family business" owned by someone I know that was facing a substantial estate tax bill wasn't really a family business at all. It was owned and managed by an older person -- often with a spouse -- but the kids had no interest in it. Usually the business was a successful retail operation, but the kids were all professionals as adults and never wanted to work the long hours in the business the way their parents did.
When you read these sob stories about families that are forced to sell the family business to pay the estate taxes, keep in mind that many of these businesses -- perhaps even most -- would be sold by the next generation anyway, for the reason I describe here.