If you don’t mind looking like the geekiest kid on the block (and for people who cart around a PDA with a boatload of accessories, that probably isn’t a top concern). the Half Keyboard, from Matias (905/265-8844, www.halfkeyboard.com ), may be for you. Most Palm and Visor users have to master the art of Graffiti if they want to enter data quickly. But the $99 Half Keyboard is your ticket back to something approaching familiar text entry. Plug what looks like a sawed-off laptop keyboard into your PDA, and let half the traditional number of fingers do the walking. Learning to use the Half Keyboard is surprisingly easy if you can touch-type. The sound of one hand typing just got a lot zippier.