Once, in the days when PDAs lasted a whole month on one battery charge, I had a Palm IIIx. I forget how many PDAs and smartphones I've had since, but the M68k-based, greyscale (mostly black & white), 160×160 little plastic box was probably the best PDA I've ever had, and the only PDA I've ever written software for. I liked writing software for PalmOS. It was simple, fun, and productive. But then, I've always liked programming platforms with limits, where you can take full advantage of the hardware. I have three rather simple applications for Palm devices. They are all available with source. As always, they are all distributed under the terms of the GNU General Public License. Though they're obviously of no use to anyone these days!
BEFH (Bastard Excuse From Hell) is a BOFH excuse calendar. It comes with an extensive collection of excuses from the famous telnet-based excuse server, and a Perl script to add your own excuses to the database. It features the infamous Scary Devil Monastery coat of arms (European etherkiller sable) and the Monks' favourite unit of suckitude (Lovelace, Ll).
Solo is a very simple and small puzzle for Palm devices. Remove pieces from the board by jumping over other pieces, until either there's only one piece left, or no moves are possible. This version contains seven diﬀerent board setups to try. Includes English and Greek version of the application, plus (badly written) source code (GCC).
Resist! is a resistor calculator. It has a few useful features for people who mess with electronics. It oﬀers two-way operation, decoding and encodes resistor colour bands. It supports E-series (currently E3, E6, E12 and E24) so you can choose appropriate components. It also approximates resistors to match E-series preferred values, and provides both scientiﬁc and engineering notations for resistance.