Using OP25[1] with RTL-SDR[2] dongles to implement scanners for trunking P25 radio systems on a computer. And as a sidebar to that, listening in on geographically remote public safety radio systems using Broadcastify[3]. It's basically the old "radio scanner" culture, but taken online and distributed worldwide. People listen to all sorts of stuff, but given my background as a former firefighter and former 911 dispatcher, my main interest is listening to public safety dispatch stuff.
That said, another commenter below mentioned modern "phreaking" and how it's become more radio centric... and while I won't admit to doing anything illegal, let's just say that there's some interesting stuff you can do / look at / listen to these days, especially with ubiquitous and inexpensive SDR hardware and related resources. See the recent story[4] about the KrakenSDR[5] passive radar stuff, and some of the papers that are out there about P25 security flaws, some of the automobile hacking stuff that's RF based, etc., etc. There's a fascinating world out there buzzing around on invisible electromagnetic fields... and you can tap into it with a $30 dongle and a Raspberry Pi (or your PC).
One of my other interests is retro-computing. I bought an Atari 800 to mess with a while back, and I've been dorking around with some stuff related to building a Z80 based retrocomputer for a while. Sadly that latter project doesn't get many cycles of my attention these days but when I have a free minute here or there or need a distraction, it's something I can play around with.
And last, but not least, I do still enjoy spending a little (very little) bit of time on MUD's[6] and IF[7] games now and then. In terms of MUD's, my current favorite is Avatar[8], and in terms of IF games I've been picking at Battlestar[9] for a while now.
That said, another commenter below mentioned modern "phreaking" and how it's become more radio centric... and while I won't admit to doing anything illegal, let's just say that there's some interesting stuff you can do / look at / listen to these days, especially with ubiquitous and inexpensive SDR hardware and related resources. See the recent story[4] about the KrakenSDR[5] passive radar stuff, and some of the papers that are out there about P25 security flaws, some of the automobile hacking stuff that's RF based, etc., etc. There's a fascinating world out there buzzing around on invisible electromagnetic fields... and you can tap into it with a $30 dongle and a Raspberry Pi (or your PC).
One of my other interests is retro-computing. I bought an Atari 800 to mess with a while back, and I've been dorking around with some stuff related to building a Z80 based retrocomputer for a while. Sadly that latter project doesn't get many cycles of my attention these days but when I have a free minute here or there or need a distraction, it's something I can play around with.
And last, but not least, I do still enjoy spending a little (very little) bit of time on MUD's[6] and IF[7] games now and then. In terms of MUD's, my current favorite is Avatar[8], and in terms of IF games I've been picking at Battlestar[9] for a while now.
[1]: https://github.com/boatbod/op25
[2]: https://www.rtl-sdr.com/
[3]: https://www.broadcastify.com
[4]: https://news.ycombinator.com/item?id=33581696
[5]: https://www.crowdsupply.com/krakenrf/krakensdr
[6]: https://en.wikipedia.org/wiki/MUD
[7]: https://en.wikipedia.org/wiki/Interactive_fiction
[8]: https://www.outland.org/news.php
[9]: https://en.wikipedia.org/wiki/Interactive_fiction