President Bush recently announced that six new countries will be added to the Visa Waiver Program list, allowing their citizens to enter the U.S. for short visits without getting a tourist visa in advance.
The countries include South Korea, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, and Slovakia. Some last administrative details need to be dealt with, but it's expected that citizens of these countries will be able to start taking advantage of this new privilege in November of 2008.
(For details of the benefits and responsibilities of the Visa Waiver Program, refer to Nolo's immigration products.)