[fsckboy]

two years earlier it was Google Buzz. two years before that it was Google Wave.

[radlad]

I don't recall Buzz or Wave having the Circles feature that many (including myself) miss from Google+.

[starkparker]

The closest thing that I remember within a Google product was actually Google Reader's optional friend-of-a-friend visibility on shared items/comments. A lot of little circles-like communities that sprung up around individual people.