A "die-hard" Windows user spends a month with Mac OS X. I've lost interest in most Mac OS X review articles, but this one gets a link for its details. The author, being a Windows user, loves keyboard shortcuts, and found some great ones I didn't know about. I'll re-mention some here as Newbie Mac OS X tips:

• To type letters with accents in Mac OS X (such as é): Alt-e followed by the letter. In pretty much every application, Alt-e will show a little accent sitting by itself with a darkened background, which is replaced by the proper character when you press the letter. Similarly, letters with umlauts (ü) are Alt-u letter, and letters with tildes (ñ) are Alt-n letter, both of which I got on my first guess after reading about Alt-e. I'm so glad to finally know how to do this in Mac OS X (and yes I'm dumb for not having figured it out).
• The task switcher appears when you hold down the command key and hit tab. I knew that. With command held down, you can hit tab repeatedly until an app is selected; releasing command will make the app active. I knew that. What I didn't know: Other keys do things while command is held and the task switcher is displayed: "q" to quit the selected app, "m" to minimize all windows for the app, and "h" to hide all windows for the app. Task switcher stays up so you can kill or hide several apps quickly this way.
• Finder keyboard shortcuts: To go up in a folder path, command-up. To enter the selected folder, open the selected file, or start the selected app, command-down. To rename the item, hit Enter and type.
• You can select text and images and subsequently drag them from another window without giving that window focus (making it the active window) by holding down the command key while you do it. Assemble an e-mail or blog entry from stuff in multiple windows without extra clicks or keyboard manipulations of the clipboard.

I'm considering tearing out all the pages of David Pogue's Mac OS X: The Missing Manual and reassembling them as a page-a-day desk calendar.