the interesting thing about this is how they decided who are the most famous scientists: Google Books.
It has been said that massive computers and huge banks of data may change the scientific method: you don't need to start with a hypothesis, just let the computer crunch a big pile of numbers and something interesting will fall out.
In this case someone studied one third of the books in Google Books, going back 200 years and calculated the fame of scientists based on how often each was mentioned in books. The measurement standard was Charles Darwin: the average number of times he has been mentioned per year since he turned 30 is a Darwin (D). Most others are measured in thousands of that, or milli-Darwins (mD). There is a link to the data so you can search for your favorite name or phrase (be careful, it is case sensitive).
By the way, the lovely graph by chazmatazz has nothing to do with Google Books or the Science Hall of Fame. I just liked it..