What are some examples of incentives you used to keep top employees as per the recommendation in the book “How Google Works”?

Question details (orig. on Quora)

In their book “How Google Works”, the authors recommended that startup founders should do their best to keep top employees. For example, in Google, they offered a key employee, who was about to leave, the opportunity to attend founders meetings. This kept him for two more years. What other incentives did you offer your key employees who were about to leave?

Answer by Dan Walter

I think the key answer to this question is “Play Offense.”

By that I mean, don’t wait until a key person is considering leaving to try and “save them. Talk to your key people and learn what they need, want and what motivates them to excel.  Most times it is a surprisingly easy to put things in place long before anyone would ever consider looking somewhere else.
Most of the programs I have seen to save leaving talent have been failures, or, at best, very temporary. I had a boss years ago tell me that you can always get back someone’s mind, but if you have lost their heart you will probably never get it back.
Communicate early, often, consistently and passionately. This will allow you to put things place to stem the flow, or prepare things to be ready in the event someone expresses a desire to leave.