The Economist has a fascinating article regarding the abuse of power. Some very clever psychologists designed an experiment to test how individuals use and abuse power and the results were quite interesting. Though not strictly game related, the article is an interesting commentary on the worst type of person to wield power and who is the best. If nothing else I found its insights useful to better understanding the corrupt and powerful. Two groups that often appear in RPGs.
Trask, The Last Tyromancer