I like the 23 Things approach to Professional Development within a library/school setting. I think that it mirrors a lot of successful badge systems out there in that it provides discreet milestones throughout a more drawn out process. Each step might only take a few minutes, but depending on the interest level of the individual, they can spend as long as they need to on a task to get what they want out of the exercise. I also like that it encourages a sense of play with regards to technology. So often we have a mindset that there is a right and wrong way to operate a program, but there is a lot of trial and error involved in computing and I think that the best tech programs make room for that sense of play. I just have to give one more shout out to badges in that they can provide the same modules along with evidence for work that was done to complete the modules.