• Don't spend more than what you have to on what doesn't matter, but spend everything you can on what does.  In several instances, the company could have spent loads of money doing things just like other companies and spending money on things they thought they needed to. Instead, they saved money on things they could do cheaply themselves, and invested as much as they could in the things that made their service unique. Without this, they couldn't have acheived the rapid and massive growth that they have.
• Go viral with a really remarkable product. I don't know whether the founders of Google ever read anything by Seth Godin, but they certainly practiced his ideas. They created a truly remarkable product, and spent virtually nothing on marketing and advertising. They gained new customers just from the referrals of satisfied users.

the story continues...