I just checked out a cool dot org site that's planning to scan classic media periodicals.
They just gotten off the ground but already have around 500,000 pages scanned (although not all are available yet).
I just love these old magazines and although what they have online is primarily cinema stuff, they plan to scan and make audio related classics available (I guess "Talking Machine World" and "Radio Daily" are just around the corner).
I've only just started to explore what's there but I'm enjoying "International Photographer" which is under the Technical Journals heading.
http://mediahistoryproject.org/