Gates If you would like a review of logic gates and Boolean Algebra, then you may want to check out this website published by Queen's University Computer Science department.
Transistor PBS dedicates this site to the invention of the transistor. They follows its development from the discovery of the electron to integrated circuits and beyond. Check it out for a great overview of transistors!
Integrated Circuit Texas Instruments pays a tribute to Jack Kilby, the inventor of the integrated circuit. This site describes how the invention came about and its impact on the world today.