Danielle Carpenter from the Botstein Lab gave an excellent talk about the basics of sequencing, from where it all started to where we are headed.
The slides are attached to this page.
Figures primarily taken from:
Sequencing technologies — the next generation, Metzker, Michael L., Nature Reviews Genetics 11, 31-46 (January 2010) | doi:10.1038/nrg2626.