Here are some of the sites I've found:
palm.comAnn Johnson was using a Compaq iPAQ with ArcPad (see handhelds.org comparison chart. See ESRI's page on the combination, and the Special Offer, which is pretty steep... but here's a review that makes it look pretty tempting).
HandCarTM Data Transport Software for the Palm, and a page of links to exemplary applications
Introducing ArcPad and ArcPad Discussion Forum
It will be a challenge to put together a combination that works and has the flexibility to support the things one imagines wanting to do, and the resulting package would soon be obsolete... so perhaps this isn't worth spending much time on.
Steve Desjardins showed me the HP Jornada 540, which MAY run ArcPad (and it looks like trying to load it is the only way to find out... according to the various things I've seen, the Jornada's Hitachi SH3 processor is on the ESRI list).
Macgpspro seems to sell a USB data cable ($64.99), which might allow connection of Garmin 12 to the device.
Sure enough, the Jornada 540 runs ArcPad with no problem. And thanks to Chris Connors' page of instructions I now have the link between GPS and ArcView working.
Looks like one of these is in my immediate future. Some URLs:
My Compaq iPAQ arrived a week or so ago, and I've been experimenting with some of its conventional powers and contemplating what it might be used for outside of those. The Strongarm chip has a LOT of power (see hardware documents ), so it seems obvious that some people would be hacking [good sense, not bad...] the hardware to extend what the iPAQ can do. Some Web searching disclosed a glorious elaboration of that very thing:
wearable computer and connecting the Garmin 12 and iPAQ archives (the presiding genius is Ralf Ackermann)
and Twiddler chording keyboard ("...With the optional "Happy Hacking Cradle", plug in the keyboard PS/2 connector from the Twiddler2 and type on your PALM PILOT! Finally, take notes at a meeting in a fast as well as discrete way." [emphasis added...]
...and I happened on this interactive Earth view and cache it here for now... and GPS Hacks and homebrew cable
...and iPAQ Linux
Tyler gave me several Devices, including an HP Jornada 820 (link to HP's site on same) which seems to have a Strongarm chip... here's a link to the manual