You can watch Venus crossing the sun live on:
Astronomy Picture of the Day June 5, 2012
Here's the beginning:

"This transit is the rarest type of solar eclipse known -- much more rare than an eclipse of the Sun by the Moon or even by the planet Mercury. In fact, the next transit of Venus across the Sun will be in 2117.
Anyone with a clear view of the Sun can go outside and carefully view the transit for themselves by projecting sunlight through a hole in a card onto a wall. Because this Venus transit is so unusual and visible from so much of the Earth, it is expected to be one of the more photographed celestial events in history.
The above live image on the Sun is being taken by the Earth-orbiting Solar Dynamics Observatory and can be updated about every 15 minutes."