For me specifically, shortwave radio. I still have a R-75 hooked up although I don't often use it anymore. I used to have a R-390 and its "mobile" cousin the R-392.

I've found the audio quality has little or nothing to do with the appeal of listening to foreign lands, so listening over the internet has had little if any change in that hobby vs using a radio. Although I do get most of my non-tech news from the BBC now, so I do appreciate the podcast feeds, something you could never do with radio.

I think most HN readers would appreciate BBC Radio 4's "In our time" program. Not every episode, especially not the more science/tech oriented, but most episodes are entertaining / mind expanding. I get it as a podcast via a RSS feed.

I would think all the startup opportunities relating to podcasting are long since used up? There seems to be a way to monetize anything people spend time/money/effort on, and at least some people do that with podcasts, so logically there must be a way to make money off them...

I'm also a shortwave fan, and I also find it less interesting as time passes. But there's a concrete reason -- there are fewer interesting shortwave programs, mostly in response to the rise of the Internet, podcasting and satellite radio.

Many shortwave bands, once teeming with interesting and useful content, have been taken over by niche broadcasters like religious groups, or ordinary broadcasts that have shifted to the shortwave bands from the AM broadcast band in tropical areas to avoid excessive noise. Overall, less interesting shortwave content.

Apropos of nothing, for years I believed that one of my favorite AM radio stations for long-distance reception (KGO near San Francisco, 810 kHz) had its frequency to itself -- was a "clear-channel" broadcaster. I recently discovered that this hasn't been true for decades -- there are now 182 U.S. domestic AM stations on that one frequency. I was shocked.

Ditto.