There is an excellent new input hack for the Zodiac [zodiacend, zodiacreset] (and other full screen PalmOS
devices) called Virtual Thumbboard. When you press a configurable trigger button such as the right shoulder button on the Zodiac, a virtual thumb-sized keyboard reminiscent of the Treo 650 keyboard appears on-screen. The keys are remarkably easy to use. Come to think of it, Virtual Thumbboard is the fastest PalmOS input method I've ever used, and I'm pretty skilled at writing in Palm graffiti.
Note that Thumbboard is still in early beta. While it works well with most of my apps, it also crashes SnapperMail and Xiino [xiino3.4, xiinodead, xiinooffline]. The developer is very active and responsive to feedback, however, and I'm sure he'll fix the crashes before the app goes final.