As many people in the software craft movement have pointed out, it's very hard to focus on reflective improvement while you are coding. In fact, the nature of your work (maintenance, time pressure) may make it hard to develop specific skills like design or clarity of code.
So why not do specific exercises outside of work, designed with the intent to sharpen our thinking - perhaps in public under scrutiny?
Micah Martin has proposed such "katas", based on martial arts. It's interesting stuff and there's video.
What are your favorite developer (or maybe test) katas? I intend to make a list.