Have you ever seen Google advertising?!

I was just reading a post by Jeff Jervis in the famous blog, BuzzMachine, titled Try life without Google, France. It was a nice post; though I missed that all! Why? Because, while reading the post, there was a paragraph as,

This anti-Google attitude comes from an apparent sense of entitlement that we see clearly in France but also elsewhere: Google owes us. We are losing money from advertising and Google is making money from advertising...

And, though, I read completely the post, but I was thinking entirely that why doesn't Google advertise for itself? I have never thought about it before, all businesses throughout the world, do advertise for their products, but not Google, or actually, I have never seen an advertisement, for example for Gmail, GoogleMap, GoogleDoc, YouTube, Blogger, etc. But why?