As for periodicals that have a paper version and some emphasis on management/project management within an IT context (some with lighter coverage than others), I read the following:
I do, however, read all of those online.
Other online periodicals that I read regularly come from the PMI itself; these are all worth the price of membership (to me):
To continue answering your question "where do you learn from?", my answer is that while I glean information and accumulate knowledge from always paying attention to what is circulating around me (such as by reading these periodicals), I learn the most in conversations with others through local meetings and presentations, #PMChat on Twitter, and the articles/information shared via membership in PMI Communities of Practice. Specifically:
I realize several of my answers are specific to PMI membership (which is different than PMI Certification -- you can be a member and have access to all of these benefits but not be certified) but that's my answer for me. I am sure that other organizations have similar benefits.