This is a list of countries in the Visa Waiver Program as of October 2012 as follows:
Andorra
Australia
Austria
Belgium
Brunei
Czeck Republic
Denmark
Estonia
Finland
France
Germany
Greece
Hungary
Iceland
Ireland
Italy
Japan
Latvia
Liechtenstein
Lithuania
Luxembourg
Malta
Monaco
The Netherlands
New Zealand
Norway
New Zealand
Norway
Portugal
San Marino
Singapore
Slovakia
Slovenia
South Korea
Spain
Sweden
Switzerland
Taiwan
United Kingdom
Travelers from these countries may visit the USA for tourism or business without a visa and may stay for up to 90 days. They must first receive authorization through ESTA (Electronic System for Travel Authorization). All persons traveling on the VWP must have a machine-readable passport. The passport must be valid for at least 6 months beyond your intended stay.
Short trips to Canada or Mexico do not restart the 90 day clock. This means you can’t make a quick trip to Canada or Mexico to restart your 90 day visit.