Old Cardboard is the only one I subscribe to.
I also like reviewing the articles in "VCBC" or Vintage & Classic Baseball Collector. Although you wanted publications still in print - VCBC is out of print, having ended publication in June 2004 - this magazine has a lot of good articles on sets from the 50's, 60's & 70's. You can find a number of copies on eBay - and the articles are still fairly contemporary. The hardest part about these issues is finding an Index to tell what each issue was about....so you know what to search for....if you are doing a topical search. I have not been able to locate an issue by issue summary to date. A summary of the sets covered is detailed in the thread noted below, but it is by no means comprehensive. The old N54 thread is here:
http://www.net54baseball.com/showthread.php?t=91711
VCBC tended to cover as much about memorabilia, player profiles, etc. It was one of the few magazines to cover areas I knew nothing about like Tintypes, etc.
Z