Actually, all Treos still have Graffiti installed in the OS - just no way to access it via any of the included software or screens.
~ insert how you feel about this brainless concept here ~
Meanwhile, while I've not used it, I've read good reports about the freeware
Graffiti Anywhere and it rates 5 stars from users at PalmGear.
GA's own site is here -
http://www.escande.org/palm/GrfAnywhere/
Instructions seem a bit convoluted, but if its as successful as it seems by reviews, I guess you get used to it. And its free!
Version 1.5.9 is good for the Treo 680.
And speaking of lost screen input software - you do know that Palm's 'old' NotePad can be used on a Treo? From a machine of your own or a friend's, access the NotePad files (Note Pad and Note Pad_enUS) via FileZ and beam them across to the Treo.
You won't be able to view Note Pad items in the current crop of Treo Palm Desktops, but hotsync does back them up.