I have a Handspring Visor Prism ($300 for the first one) and *love* it.
So much that, when HS killed the line, I rushed to COSTCO and picked up two spare units for $99 each.
I upgraded them ( Huey, Louie, and Dewey ... "Silent Running" ) to 16 Mb RAM.
I was appalled that HS killed the Prism line just to force us to buy the crappy TREO things.
As a teacher, I use the EyeModule2 camera to get very nice JPEGS of my kiddies for seating charts, portfolios, projects, morphing fun etc. I also take quick snapshots, at 640 X 480 full VGA , of documents to zoom-view with AcidView instead of xeroxing or writting notes by hand -- cuts down on interruption time while I try to teach.
I could even do time-lapse movies over a whole day , if I am absent, to check on SUBSTITUTE KILLERS that may be mascarading as angels
I also take some handwritten notes in an app that saves these with timer alarm reminders.
I sync all this to my Flat-Panel iMac and "Retrospect" it to DVD daily.
I use the VisorPhone module to call parents on the spot , when the darling velociraptors take to cannibalizing the new kid. And I can use the super memo pad to take notes while chatting with Moms.
With a Stowaway keyboard, and wordprocessor, I can compose documents at work and even e-mail them back to my iMAc.
I use a Mobile version of an electronic gradebook and will soon move to FileMaker Pro / Mobile2 for better performance and page layout.
I will use the Red-M bluetooth module to print documents and memos
remotely and to download entire gradebooks to the District computer without filling scantron bubbles until I'm blind.
I will use the Momentum II barcode scanner to process some multiple choice quizzes and to inventory textbooks. If I could tattoo the little suckers, I'd have roll-taking down pat

too !!!
And for faculty meetings, there is BEJEWELED .
-------and it's an investment and risk of HUNDREDS of $ instead of THOUSANDS for laptops and accessories. A lot smaller to carry too.
I sure hope that PDA's don't become extinct soon.
But , for my needs, I am set for the next five years or so.
---gooddog