Overloaded with Extensions -- Teng Chou Ming has released the $10 shareware Extension Overload 2.7, a stand-alone DOCMaker document that provides information about 666 extensions, 245 control panels, Easter Eggs, Macintosh error codes, and more. It's smaller than, but otherwise quite similar to, Dan Frakes's InformINIT 8.1 (see "InformINIT: Your Personal Macintosh Informant" in TidBITS-429). Although there's obviously much overlap between the two, they provide complementary information in places. Extension Overload is a 227K download. [ACE]
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-]).