From Matt Baker of UsefulCharts, this chart traces the evolution of our familiar alphabet from its Proto-Sinaitic roots circa 1850-1550 BC. It's tough to see how the pictographic forms of the original script evolved into our letters; aside from the T and maybe M & O, there's little resemblance. Prints are available. (via the morning news)
Update: Baker recently did an updated version of the alphabet evolution chart.