I think some of you might find this useful! :)
I just saw this Passport Index site that rank passports by the number of countries you can visit without Visa,
and I thought I should post the linke here.
U.S and U.K are the two most powerful passports in the world, according to this site.
You will be able to visit 147 countries without a Visa if you are a U.S. or U.K. citizen.
Here is the site where you can check any country in the world.
Unfortunately though, the site does not yet give a list of the countries that do not require Visa, .
I hope that will be listed in the future, but for now, it is for you to find out.