Snow Leopard introduced a 'click and hold' feature for app icons in the Dock, to reveal application windows with a new 'Exposť in the Dock' effect. But most keyboard lovers don't really think that's too useful.
However, you can activate the effect from the Command-Tab switcher by pressing the Down or Up keys while holding Command. After the Exposť effect appears, you can release the Up/Down keys, and then press Tab or Shift-Tab to choose from opened applications.
But choosing a window needs too many key presses: You must at least press one arrow key (Up, Down, Left, or Right) to make the blue focus box appear. After you choose a window, press Space Bar to Quick Look the window, or press Enter to bring the window to front. (Of course, you can hover and click if you reach for the mouse, too.)
While not much of a hint, for those who do not like their minimized windows taking up so much space in the Dock, now you can have them minimize into the dock icon.
Open the Dock System Preferences panel, and check the Minimize windows into application icon option. Once you do that, minimized windows will disappear into their source application's Dock icon.
If you are lazy, like me, and forgot your wireless mouse on one end of the room, and you are using a wireless keyboard on the other, it is possible to toggle this feature using Terminal. To enable this, type defaults write com.apple.dock minimize-to-application -BOOL YES, then press Return.
[robg adds: While this is documented, it's also one of the more potentially useful new features in 10.6, so I felt it worth calling out as a hint. Windows minimized into an application icon will appear with a diamond next to their names in each app's Dock contextual menu.]
Upgrading to Snow Leopard made me disappointed to see that Sound Source no longer works as a menu extra. However, this left me disappointed for only a few seconds, as I figured out that by Option-clicking the OS X Sound icon in the menu bar, you can choose your inputs! I don't recall Leopard ever doing this, or seeing it in the new features of 10.6. Enjoy!
[robg adds: This is definitely new in 10.6, and a welcome addition.]
A lot has been said regarding the new "Exposť in the Dock" feature in Snow Leopard. Just click and hold on a Dock icon, and you'll get an Exposť view of all that apps open windows.
I am not sure if this is common knowledge or not, but if you Control-click (or right-click) on a Dock item, you get the pre-10.6-style pop-up Dock menus. They are the new white-on-black HUD style menus, but with the old functionality.
Extra credit goes to the person who finds out how to set this as the default behavior.
I do not know if this counts as a hint, but with the way Snow Leopard has compressed the apps, it seems it's no longer possible to look through certain programs, such as Finder and Dock, with the strings utility in Terminal to find new hidden settings.
[robg adds: To clarify this hint, you can still run strings - someapp.app in Terminal to dump the strings (and redirect to a file, most likely). However, in that dumped file, you won't find any of the hidden defaults strings. I tested this with the Display full paths as Finder window titles hint. While the hint itself seems to work fine in 10.6, you won't find _FXShowPosixPathInTitle anywhere in the dump of Finder's strings.
If someone knows how/where/if you can find such hidden prefs in 10.6, please post -- otherwise, I think we'll see many fewer such tweaks here in the future.]
There is a bug in Snow Leopard that disables LCD (sub-pixel) font smoothing on many third party LCD displays, including models from Dell, Samsung, LG, HP, EIZO, and Lenovo. Here are the details:
Snow Leopard introduces simplified Font Smoothing options under the Appearance pane in System Preferences. Prior to Snow Leopard, the available options were:
Automatic - Best for Main Display
Standard - Best for CRT
Medium - Best for Flat Panel
In Snow Leopard, you can only choose between Automatic and Standard CRT. Since few people use CRTs these days, most users now have only one option: Automatic. The problem with the Automatic option is that OS X incorrectly detects many third party LCD monitors as CRTs, and consequently, disables LCD font smoothing.
You can force OS X to use LCD font smoothing on all displays with this Terminal command:
Bootcamp 3 adds support for mounting your Mac's HFS partitions. By default, Windows Update tries to use the hard drive with the most free space during installs. For many users, this may well be one of your Mac HFS volumes.
The way to resolve this is to unmount the Mac volumes first, leaving Windows Update only Windows-formatted volumes for use. I used XP's built-in command line program Mountvol to unmount the Mac partition. After that, running the updates was smooth sailing.
Warning: I am not explaining here how to use the system Mountvol to unmount volumes, as if you get this wrong, there is a good chance you could loose data.
[robg adds: I can't test this one yet, as I don't have Boot Camp installed on my 10.6 machines. However, I would think the contextual menu in Windows should allow ejecting non-system volumes, but perhaps that's not the case.]