Wow, this is a big week for viewable events in the sky. To lead off there is a partial lunar eclipse in the early hours of the morning (US CST), more info in the video.
However the bigger, and better timed event is the transit of Venus across the face of the sun, the last transit was in 2004 but the next one will not occur until December 2117.
Obviously just as with a solar eclipse you need to take care in observing the event, however you can see it with something as simple as two sheets of paper and a pin. Just take the pin, poke a small hole in one sheet and hold it between the other sheet and the sun. You should have the effect of a pinhole camera and be able to see the dot which is Venus as it passes across the face of the sun. Another design for a pinhole camera can be found here.
You can also view using a projection method as described here and here.
If your local weather conditions don’t permit direct observation, NASA will have a live webcast from the summit of Mauna Kea, Hawaii.
Science@NASA ScienceCasts on YouTube has a good video about it also.