GooglePlusPlus Default Circle - extension / userscript for Google+ (aka Google Plus aka G+) which adds a star next to each circle stream name. The star can be clicked to set or unset one circle stream as your default. When a default is set, going to the Stream view (which is an aggregate of all your circles) you automatically get redirected to your default stream.
So, my understanding is that the only posts that should show up in my main Stream are those created by people I've placed in a circle. Is that correct? If so, why do posts by people that are nto in a circle show up?
Note, some of these people used to be in a "Who Are You" circle, so I could occasionally check it out, but I got sick of that traffic crowding out the people I am interested in, so I deleted the circle.