List of top 100 websites in terms of Traffic. Not just for USA, for
whole of the Internet.
I need just the list only. Any link to that list will do as well.

http://www.alexa.com/site/ds/top_sites?ts_mode=lang&lang=en

This is pretty close.  The rankings correspond closely to their listed
traffic rank.  When you click on the site detail you get the traffic
rank.  You could certainly compile a list with this info.

http://www.alexa.com/site/ds/top_sites?ts_mode=global&lang=none

The results from Alexa all come from people who are running the alexa
toolbar, which I would imagine is an extremely small minority of
internet users. Sadly I don't believe there's a better resource for
this type of information (certainly not for the entire network)

You don't necessarily need a huge sample to make a reasonable prediction.  

Nielsen ratings work with only about 5000 families.  I don't know how
accurate Alexa is, but they say they 10 million toolbar users.  That's
a pretty good sample size.