* Gmail
* Maps
* Chrome
* Youtube (yes, it was acquired. But you cannot deny Google's touch pushed Youtube to the top)
* Flights (seriously, forget all the other sites)
* NGL I love their productivity side (Docs, Keep, Drive is OK I guess)
Not to mention the near countless multi-millionaires Google has created
They bought it because their competing product failed so badly barely anyone remembers it existed. I'm not so sure Google actually helped much beyond increased bandwidth for higher-quality video.
And don't underestimate how important it is to be capable, performant, and available. Outages and routinely slow performance is how you bleed customers. No doubt G had a hand in bolstering our little video site