Jonesy - 7:50 pm on Nov 26, 2011 (gmt 0)
I've often wondered about this, too.
I have a not-NEVER-linked-to-by-ANYTHING web page mainly for personal use --
local weather conditions, weather radar image, and a few local web cams.
But, I have passed the URL on to several friends (who have NO idea how to put
up a web page or a blog). Yet Google has the page indexed -- which
really is not a concern.
I'm guessing it got into the wild via
1. A Google-like toolbar.
2. A Facebook or Twitter posting.