Aced all my classes in my first quarter at Stanford, took up blogging (again!) and used (social) pre-commitment techniques to stick with it, finished a timeboxing analysis and found some interesting patterns in how I manage my time, started deliberately tracking short- and long-term goals and established systems with which to track these resolutions, and began a segmented sleep experiment (and will continue for a week or more based on how things go).
As in Joshua Blaine's original description (below), but may be used to brag about things you've accomplished either this month (December) or the previous one (November), assuming that you haven't brought it up in any earlier Monthly Bragging Thread.