(This was written ages ago. I haven't used it as much as I intended, but I've certainly used it more than the fresh set of note cards I bought with the intention of making a start on developing my knowledge of Polish with...)
After a friend bought a Palm on hearing an acquaintance sing its praises for calendaring, I thought I'd see what basic models were out there that would handle flash cards for vocabulary learning, and, as is my wont, started looking for models that take alkaline batteries — which in vintage Palms typically last a month or two versus considerably less for built-in rechargeables.
The Palm M100 was released in 2000 and sold in the UK at one point for £129.99 (according to the sticker on the boxed example I picked up on eBay) but these days you'll be lucky to get a tenner for one. It was regarded as a student toy even when the model came out, providing only 2Mb of non-expandable memory and no SD card slot. Other downsides are that they use a serial connection, so you'll need a USB-to-serial adapter on a modern PC, and models in the line that use non-rechargeable batteries usually lose the contents of their memory when power is removed (the capacitors used, in theory, to preserve the contents for a minute or so whilst batteries are switched tend to die after a year or so.) There was no newfangled flash memory in these things, meaning that a model that can't be recharged and can't backup onto a separate card if needed is only really practical for usage situations in which you dump data and software onto it in a one-way process and can do the same sync again when the batteries need to be changed. It's no surprise they're cheap now; the only worrying thing is how many people were suckered into accepting this situation at the time.
So how useful is a machine with 2Mb of memory, a tiny, tiny fraction of the 4Gb flash drive I typically carry (which itself is small these days)? For what I want, very much so, as the memory will hold thousands of flashcards, but probably not if you were hoping to keep lots of addresses, memos, books, dictionaries, etc. on it. Out of curiosity, I trawled a few sites offering freeware compatible with Palm OS 3 to see whether there was anything else funky to install... the OS is a limiting factor if you were thinking of looking for dictionary software, which tends to work with version 4 and up at best. The ideal model for those folks (that still takes AAAs) would be the M125, which has Palm OS 4, 8Mb, an SD slot, USB connectivity and a faster processor. A useful comparison of the specs of older models can be found here provided GeoCities doesn't go the way of other ancient free webspace providers.
Anyway, here's what I installed and didn't immediately delete... some of these were a bit hard to find download sources for, but I recommend browsing FreewarePalm and then googling anything the links are dead for to look for old mirrors. Or if you're really stuck, drop me an email.
Anki by Copera — one of several solutions I found; this is ex-commercial software that has straightforward flashcards plus multiple choice testing, and support for plenty of character sets. I find it easiest to build lists as a structured text file then convert them to a text file, rather than use the supplied Windows software, and there are some ready-made wordlists to download. I might try to learn the NATO phonetic alphabet at some point as well as Polish words.
Other useful stuff
Converter by Matt N. Marsh — most units you'd ever want to convert.
Stopwatch 2 by PlushWorks — counting up (and optionally down) in a readable font.
Eggtimer by Voodoo Development Dudes — counting down with a big font. Stopwatch 2 kind of does the same thing, but this has a nicer interface for it.
Asteroids by Phil Snowden — an old favourite for wasting a few minutes; wireframe asteroids to blast apart.
Pocket Sokoban by C. K. Wong — classic puzzle game. Push crates around onto the X symbols, without blocking your ability to complete each level.
Palm Willy by Ralf Brese — riffing on Manic Miner and Jet Set Willy, collect all of the flashing items in each room and get out. More levels are available as shareware, but as I'm currently stuck on the second this is unlikely to be investigated much.
MoonPhase by Steve Kienle — work out the best nights to go stargazing.
PalmaSutra by PilotFun — a selection of Karma Sutra positions with instructions, for anyone interested in what they ones they're used to are called or looking for awkward, impractical ideas.
Oblique Strategies by Lonnon Foster — read about them here.
Yoda by Pete moss — random sayings from the master.
PalmMirror by ITIL — fill the screen with black so that it reflects better.