One title that has not been mentioned yet did me a lot of good. It seems to be hard to find nowadays and rumour has it that some chess clubs have banned the book for being unethical!
Chess for Tigers, by Simon Webb second expanded edition+. It is much more about the psychology of competitive chess and hence of greater use for over-the-board players than for correspondence types like us.
Webb deals with self-analysis, getting a good idea of whom you're playing against, playing against stronger and weaker opponents respectively, guerrilla tactics, time controls and the makings of a good swindle. It is a very fun read, and doesn't encourage any behaviour which is actually not within the rules. It does make you a much more hard-nosed competitor.
