These sites are maintained by various media organizations. Some have open access, most limit free access in some way, some have a paywall for all content. One can follow most of them on social media platforms like Twitter, Facebook, etc.
Most of these magazines make at least a sampling of their content available online. LHU’s Stevenson Library subscribes to some of them (check there for most recent list).
International Opinion Magazines:
Pew Research Center Journalism Project: http://www.journalism.org/