A few weeks back I presented at Nerd Nite Sydney. The topic; A brief history and introduction to data visualisation. A friend recorded the whole thing which you can now view online here.
Even with the view being partially obscured by the audience halfway through, you can still take in the whole thing. I hope you enjoy it, learn something new and see how data is all around us and the need to understand it via visualisations is ever growing.
A lot of these visualisations that you can see in the presentations are created using Tableau. A free version, called Tableau Public can be found here. Give it a go and see what you can create.