It won't happen again until December 2117. On June 5th, 2012, Venus will transit the face of the sun. The best places to watch are in the mid-Pacific, but travel is not required. The historic event is widely visible around the world, including at sunset from the USA.
The full story can be found here: http://science.nasa.gov/
A companion video is posted below and can also be viewed at: http://www.youtube.com/watch?