A list of template letters for occasions on which one ought to apologize in writing, from Great Personal Letters for Busy People: 501 Ready-to-Use Letters for Every Occasion by Dianna Booher, published by McGraw-Hill in 2005.For not having writtenFor forgetting someone’s nameFor failing to invite friend to partyFor making embarrassing remarkFor behaving inappropriatelyFor a friend behaving inappropriatelyFor missing anniversaryFor missing birthdayFor missing funeralFor missing deadlineFor bouncing cheque to friend or relative