Prof. Phung of University of Wollongong in Australia has put together a great deal of excellent materials on teaching AVR.
http://www.elec.uow.edu.au/avr/index.php
specially check the
http://www.elec.uow.edu.au/avr/microcontroller.php
Embedded.com - Small is Beautiful
Tutorial: Improving the transient immunity of your microcontroller-based embedded design - Part 1
Tutorial: Improving the transient immunity of your microcontroller-based embedded design - Part 2