In addition to headsets/intercoms and gps, I would add satellite weather.
Our engines and airframes haven't changed much since the 1960s, but avionics have for sure, and I would put those three at the top of the list.
You can surf through old copies of Flying on Google Books, and it's interesting to see how avionics have progressed.
It was essentially VHF NAV and COM for decades. Dialing a freq without tuning and having more than a few channels were big steps, as was being able to communicate and navigate at the same time. The NAV/COM the way we know it didn't really pop up until the early 60's (360 channels, fully independent NAV/COM). The KX170s were dang fine boxes and represented the pinnacle at the time. After that, improvements only happened in degrees...like digital displays and standby frequencies.
Something like an Apollo SL-30 wasn't even imaginable.
There were complicated and cumbersome RNAV type units starting in the 60s, including some "moving maps" (they were maps...that moved...no joke). VLF and Omega were there, but essentially for transports only.
ADFs took a different path because they are relatively complicated, electronically speaking.
The next big step for GA was LORAN-C. Those boxes started popping up around 86-87, and became common in the late 80s. The boxes like the Northstar M1 and Apollo 618 were wonders. I want to say that ARNAV made the one box that could be updated by card...everything else had to be removed to be updated. It took a long time, as I recall, for LORAN to be certified even for enroute IFR. They'd published some LORAN approaches, but I want to say they never got activated.
Richman