The one constant across all these machines has been HyperCard. I've been programming using HyperCard since 1988 when my roommate bought the HyperCard Handbook. I've written countless stacks, some of which I've now been using for over 18 years! When necessary, I write a C or C++ XCMD or XFCN (or use one of the many existing ones) to speed things up. I still write tons of utility functions in HyperCard when I need to convert some data (although since I upgraded to Mac OS X, I also use UNIX filtering frequently).
I originally got a PalmPilot Pro in December 1997, and upgraded to a Palm III in July 1998, a Palm IIIc in May 2000, a Handspring Visor Prism in December 2000, a Sony Clie T415 in December 2001, a Sony Clie NX70V in October 2002, and a used Sony Clie NX80V in October 2006. I use CodeWarrior on my Mac to program the PalmPilot in C.