Google had a successful ads business before the doubleclick acquisition.

They are still more or less separate software stacks. (Disclaimer: This knowledge is outdated by about 2 years, but a significant change is unlikely. )

but it was far from supporting the whole company alone as it is now. it mostly was successful because of their search monopoly alone. they could have banners and it would have been the same before the acquisition

Source on Maps please. They bought KeyHole or whatever, fir Google Earth maybe. But Maps itself was started in-house, no?

Wikipedia says: "Google Maps began as a C++ desktop program designed by Lars and Jens Eilstrup Rasmussen at Where 2 Technologies. In October 2004, the company was acquired by Google, which converted it into a web application."

the web 2.0 interface to the bought map backend, yes I think that was original.

Flights, bought (ITA Software)