Microsoft has released Skype 6.15, which fixes two instances of crashes (one at launch and one when quitting) that were identified thanks to users in Skype’s Community Forums. The update also fixes a bug that prevented per-conversation notification settings from sticking and an issue with animated emoticons using too many CPU cycles. Finally, the release also eliminates crashes when screen sharing on a MacBook Pro (with the associated recommendation that MacBook Pro users also update to OS X 10.9.2 Mavericks). (Free, 41.5 MB, release notes)
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-]).