About a decade ago, I helped write this: http://www.powermedia.com/pilot/index.shtml
It seemed brilliant at the time and we were recreating something that had already been successful (http://www.catamount.com/NewtonApps/Aloha2.html).
There were lots of Palm users AND lots of AOL users, how could we fail?
It turns out that there were very, very few Palm MODEM users. And without the modem, it wasn't going to work at all.