Google's staff perks (like free food and 20 per cent of their working hours allowed for their own projects) are well-known, but this is an utter doozy: if a Google staff member dies, their partner will receive half their salary for the following ten years. That's a really powerful incentive not to go and work for the competition.
In an interview with Forbes, Google's chief people officer Laszlo Bock revealed that if an employee dies, half their salary will be paid to their surviving partner over the next ten years (in the form of an annual cheque). Any children from that relationship will receive $1,000 a month until they turn 19, or 23 if they continue studying. Even more remarkably, the death benefit applies no matter how long you have worked at Google.
Unfortunately for Australian workers, that perk doesn't appear to extend outside the US (though plenty of local Googlers I've known have ended up working in the US operation anyway). While costly, it's clearly an effective way of creating staff loyalty.