Official U.S. time from the Master Clock at the U.S. Naval Observatory is posted by zone on the Navy's time service website. This time is used by the Department of Defense and GPS Network. The exact time is also available at the National Institute of Standards and Technology website.
Both the Navy and National Institute of Standards and Technology websites offer animated clocks, and Google displays the correct time as a search result for the term "time". Time conversion sites like timeanddate.com show the current time in the United States and other countries. These sites also offer other features like time zone conversion, meeting scheduling and event announcements.