I'm trying something new. Since I receive a ton of information that doesn't warrant detailed exploration in TidBITS, I'm starting a new section called TwoBITS that will address deserving announcements but will do so in only two sentences (and contact info). Let me know how you like it after you've seen a few.
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-]).