Aaah, A familiar, yet welcome redux of days gone by.
My Zaurus is the ZR5800, so I was fortunate enough to get the spreadsheet application, PenCell 2.0.
Mine didn't come with a modem, but I bought a 14.4 PCMCAI card modem that faxes just fine (I've never bothered with e-mail. I'm just never to far from a PC with internet access.)
I keep my 2Mb SRAM card in the Z, because it holds my Z-Calc program, and provides extra file areas (and doesn't use the Z's battery!) I also keep a could of 3,840Kb Linear Flash Memory cards for backups and file storage. (They can also hold programs.)
My uses include three contact areas: 1) Family and Friends; 2) Projects; and 3) Networking contacts.
My three Data files are an electronic version of "Hitchhiker's Guide to the Galaxy", published in Ursa Minor, A Franklin Planner File, and a Yellow Pages (probably the most massively useful of the lot.)
I, too, make much use of the linking features between applications, and especially the "Filer" program to hold it all together.
My spreadsheets are useful for many things, including self programmed games like Yahtzee, BlackJack, Minesweeper, etc.
The Documents applications is great because I can hold many texts for reference, and IR them to IR-capable printers as needed. (I'm just beginning to use Outlines.)
I'm especially pleased with the One-Password-Locks-All secret documents feature. All my user names and their passwords are safely tucked away for easy reference.
The To-Do list is terribly useful and many times I duplicate them in the appointments calendar, just for the alarm.
I have purchased a Psion Diamond Mako, and it is pretty neat, but the Z is the one I carry around.
Doug