Stop what you are doing and head to Historypin!

A completely genius idea that is being used for good! Hooray! Historypin allows GoogleMap StreetView to meld with Picassa photo repository to create a verifiable comparison for any site in the world (that has been Google-SV mapped) with images of it in bygone times. Plus they are developing a way of informing your digital camera of when you are in the correct position to replicate a famous photograph (such as the VJ Day kiss in Times Square).

Simply marvellous!