That this was the the first thing listed did not make me very interested in reading on.
Favorite browser modification: set default page to about:blank
Favorite browser modification: set default page to about:blank
I can add any content I want there.
Then if it phones home I have only myself to blame.
You can probably also style about:blank to have whatever you want in it when it loads. I'd imagine that is done differently depending on the browser you're using.
On the other hand, I'm not sure why you'd want to when you can just set your new tab page to a custom page of your choosing.
Edit: clarification