BBC has a reputation for quality educational resources.
The History of the World in 100 Objects is a downloadable radio series of 100 short programs
in which scholars discuss the history of the world illustrated with 100 historical artifacts from the British Museum.
Hundreds of items from other museums and individuals have been submitted to the interactive timeline.
Radio downloads are available in both low and high bandwidth versions.http://www.bbc.co.uk/ahistoryoftheworld/