Is it just me ..
.. or did we skip over the entire Palm ecosystem?
Palm pilots had their own fanclub :). I personally was more in the Psion camp because especially on the Organisers and Series 3 you could just write your own software, on the device, and with a bit of trickery all your data was available to mess around with. Then the programming language "grew up" (i.e. became unavailable for the average end user who just wanted to do something with their data).
The Psion Organiser II was good training for your memory because you'd have to hold most of the code in your head (a 2x16 or later 4x20 screen is a tad small :), but you could code anywhere, any time. I'd love a language like OPL for Android and iOS, because it would enable a lot of people to enjoy the fun of quickly hacking something together instead of having to learn high grade programming from scratch.
Having said all that, I liked Palm. I had a few..