The standards for training have been much discussed in this thread and many others, and so rightly so. Skills reduction and focussing on the demanded/obligatory parts are regularly mentioned.
Next to those, there are knowledge parts and voluntary choices that help define and maintain the quality of pilots. So what is available to pilots who would want to know more and do even more to better themselves. One element of the safety culture in a number of major airlines was a set of bulletins that were regularly and freely shared with the technical, operational and pilots communities. I wonder what happened to those in other airlines over time.