Cory Doctorow is Outreach Coordinator for the Electronic Frontier Foundation. He's been using Apple computers since 1979 and has a 27-pixel-by-27-pixel tattoo of a Sad Mac on his right bicep. He won the John W. Campbell Award for Best New Science Fiction Writer at the 2000 Hugo Awards, and his first novel, Down and Out in the Magic Kingdom, will be published by Tor Books next Christmas. He is the co-editor of the weblogs Boing Boing and Forwarding Address: OS X and is a frequent contributor to Wired. (August 2002) <http://www.boingboing.net/>
Go Back and Forth Fast in Preview
If you're reading a PDF in Apple's Preview software, and you follow a bookmark or an internal link to move around within the PDF, you can quickly return to where you were by pressing the keyboard shortcut Command-[ (that's Command-Left Bracket). Or, you can choose Go > Back.
The command works iteratively, so you can go back to just the previously viewed page or if you issue the command again, to the page before that, and so on. There's also an equivalent Go > Forward (Command-]).