The last time Venus passed in front of the sun was on June 8th 2004. We were living in London and I used a pair of binoculars, a piece of cardboard and a camera to record the event (a guide to using this method is here).
The transit as photographed by me in 2004In the past the transit of Venus has been used to calculate the distance of the earth from the sun, and although that distance is now known to within about 30 metres (modern technology, eh...) the transit still holds scientific interest. This year they will be measuring how much the level of light from the sun drops during the transit and use this in the search to find planets circling other suns, amongst other things. For instance, a side effect of the measurement of the 1769 Transit of Venus was Captain Cook claiming Australia for King George III.
So don't miss it - it really is the last chance to see. Just don't look at it directly or it will be the last thing you ever see.