For all of you geek out there, there are 2 interesting choices for you from Fossil. One is watch running the good old familiar Palm OS and other with MSN Direct service. Check them out at http://www.abacuswatches.com/
Good news is that their street price is as low as $50, you can get some good bargains from amazon.com too.
I think it can be even used for small applications. PDA model has same memory as Zire21 model, that is 8 MB. Field Force Solutions targetting these PDA watches can be offered for small corporates which do not want to spend a huge some of money to just get the PDA hardware.
You can read a complete review of Palm PDA watch at http://www.theinquirer.net/?article=31360