A separate keyboard isn't a very portable solution for those with an aversion to the stylus, but an onscreen keyboard is much more practical. Mini-Keyboard is a nifty little program that displays a small QWERTY keyboard on the screen, which you can type on. Hunt-and-peck typists can use the stylus, and the keys are just large enough to let you use your thumbs too.
Unfortunately, activating the keyboard requires a stylus stroke and text entry appears on the program's own screen rather than that of the application from which it was activated. In portrait mode, the keyboard also uses a novel compressed layout that takes a bit of getting used to. Switch to landscape mode, though, and you get the real deal.
Mini-Keyboard works surprisingly well and is reminiscent of typing on a Psion Series 3. The only real downside is that it leaves fingerprints all over the screen, making a screen protector a non-optional extra.