Three Rock 103 Wake-Up Crew Cassette Tapes (Audio, 1997/1998/1999)
You can listen to late-90's morning zoo cassette tapes from Memphis, Tennessee here.
Gunsmoke (Radioplay series, 1952-1961)
You can listen to this western radio series here.
You can read an alternate-universe webcomic adaptation, Altered Frontier by @mercuryhat, here.
Radios of the Baby Boom Era (Books, 1991)
You can digitally borrow most of the six volumes here.
PR Gnus of the World (Audio, Mr. F. Le Mur, various years)
The World's 3rd Greatest News Source, Presenting Yesterday's News Tomorrow - a series of bizarre audio mashups cut together from NPR radio broadcasts. You can listen to it here.
By the creator of Believe It or Kill Me, the Ripley's Believe It or Not radio micro-show mashup (warning: the link in this paragraph is a massive rabbit hole from which you may not emerge for days, weeks or months.)
Over the Edge Radio (Audio, 1981 onward)
Over 1300 episodes of the radio show, from the 1980's to the 2010's. Plunge into the bizarre alternate universe of the Universal Media Netweb and paint the town not red, but squant. You can listen to it here.
Radioamator (Magazines, 1950-1978)
Check out the graphic designs on the covers of this Polish radio hobby magazine. You can read it here.
Tip: 1960 is the most diverse era cover-wise, with a different design every month.
Believe It or Kill Me (Audio, Mr. F. Le Mur, ????-????)
Minimalistic yet bizarre mashups of the Ripley's Believe It or Not radio micro-show. Listen to the whole run here.
As featured in the Church of the Subgenius' bizarre radio show, the Hour of Slack. Listen to the surface archives here, and even delve deep, deeper, yet deeper.
('Deeper' link requires liberal use of the Wayback Machine - feed Ogg download (not 'listen') links into it, then grab an early version of the file to avoid a 404 error. Ain't time travel grand?)