[prakash]

once you have paying customers it's hard to say those things :-)

[nailer]

Customers pay with Google now, supplying them with private information and attention for their advertisements.

This is the same model almost every magazine and newspaper, where the cover price merely offsets a portion of the printing costs.

[SwellJoe]

Google does have paying GMail customers. It's $50/user/year for business class GMail.