While this worked well, it required you to activate Exposé before pressing Command-Tab. In Snow Leopard, this process has been greatly improved. While the old method still works as before, you can now activate Exposé's Application Windows mode pressing Command-Tab. Don't try to do this with the Exposé key on your keyboard, though, because that won't work.

Instead, keep the Command key pressed, release Tab, and then press either the Up or Down arrow. This will switch you into Exposé's Application Windows mode for the currently-select application in the Command-Tab app switcher. At this point, you can release the Command key, too, leaving no keys pressed.

From here, press Tab (and Shift-Tab) to cycle forwards and backwards between applications (while remaining in Exposé's Application Windows mode). When you see the window you'd like to activate, press one of the arrow keys to select it--the selected window will gain a blue outline (or you can use the mouse/trackpad, of course). To activate the chosen application with the selected window, just press Return to exit Exposé mode, and the selected window will come to the foreground.

Another nifty Exposé trick in 10.6--and this works both in the above example, and when using Exposé's normal Application Windows mode--is the ability to Quick Look a window with Exposé active.

Make sure the window is selected (shows a blue highlight) by pressing an arrow key first or hovering over it with your mouse, then press the Space Bar. The selected window will zoom in, just as with Quick Look in Finder, but you'll remain in Exposé mode.