This isn't strictly speaking "this month", but more "since the last time this thread was around", perhaps three or four months. (ETA: actually, the last such I took part in was October '13.)
Built a 3D printer from a kit. Learnt enough G-Code and OpenScad to be dangerous. Designed a few parts of my own, including some that replaced original parts.
Lost about 6 kilos from my max weight. Anecdotally, what seems to have worked in my case was eating lots more vegs, liberal amounts of meat, and about half my previous quantity of carbs. Also increased exercise a fair bit, incorporating a lot more walking (to or near the oft recommended 10K steps a day) in addition to a weekly run (typically 10K). One of my major objectives was to not feel like I'd gone on a diet, but instead to rewire my preferences so that eating whatever I enjoyed would lead to weight loss. I worked quite a bit on identifying and removing the trivial inconveniences that were keeping me from enjoying vegs and salad more often.
Switched banks. Sounds easy when you write it like this but it's an insane amount of hassle.
You could have created the 'Monthly' bragging thread if you had a suitable opportunity.
Your job, should you choose to accept it, is to comment on this thread explaining the most awesome thing you've done this month. You may be as blatantly proud of yourself as you feel. You may unabashedly consider yourself the coolest freaking person ever because of that awesome thing you're dying to tell everyone about. This is the place to do just that.
Remember, however, that this isn't any kind of progress thread. Nor is it any kind of proposal thread. This thread is solely for people to talk about the awesome things they have done. Not "will do". Not "are working on". Have already done. This is to cultivate an environment of object level productivity rather than meta-productivity methods.
So, what's the coolest thing you've done this month?
(Previous bragging thread.)