relaxdiego Mark Maglana's Technical Blog
This may not be a slideshow, but it certainly is a good example of how to present numbers. Notice how this infographic does away with fancy graphics and yet gets the point across. I'd recommend using this for any comparison data. Chart purists might have a beef with the fact that it uses areas instead of the more technically accurate bar charts, but I think that it's really effective in getting the point across.
Original infographic here.