[nostrademons]

A little after that. I'd put the heyday between 2003-2010, starting with the GMail launch and ending with the Chrome & Android launches. That period includes GMail, Maps, Scholar, Orkut, Reader, the acquisitions of Blogger/YouTube/Docs/Sheets/Slides/Analytics/Android, Summer of Code, OAuth, Translate, Voice Search, search suggestions, universal search, Picasa, etc. Basically I can look at my phone or computer and basically everything I routinely use dates from that period.

[mistrial9]

GMail, the service that tells every user that they will be indexed and profiled personally for ad leads? that is an achievement ?

GMail was one of the red flags for many that "don't be evil" was not going to be what it appeared. History says that this kind of mass profiling never ends well.

[pests]

Gmail doesn't show personalized ads for some years FWIW.