Do you know what I miss from Mac OS 9? Popup folders. If you had an open folder/window, which you need often, but you don't want it open all the time, you could just drag it to the bottom of the screen, and it would turn into a little tab which popped up a window/folder connected to the edge when you clicked on it.
I fould this way more useful, simple, fast, and user-friendly than having folders in Mac OS X's dock.
The closest I've found is a nine-year-old tip from DrClaw:
Here's a substitue for pop-up folders. It works best with Finder windows, but can be applied for others.Take a window, resize it to a small size but so that you can still see the name of the window, and drag it to the bottom on the screen (should only see the title bar). Now hitting zoom will reveal the window in full. Hitting zoom again will return the window to the bottom of the screen. This is easier to use when the dock is is located on the side of the screen.
I'm amazed that this still works after all these major updates of OS X.
It's pretty close top popup-windows, but it does not collapse again automatically, and you have to use the Maximize button instead of anywhere on the "tab". And you have to drag it down again after putting something in it. So not super-great.
(Also it would be more ideal to have a utility which could use the sides of the screen also, since (having many apps) I prefer to have the dock at the bottom.)
Update: I found something called "Sticky Windows" that sounded perfect. But it does not work with Snow Leopard... sigh...
Update: ... I'm finally trying the famous Finderpop though (review). It's only a beta for Snow Leopard, but a very late beta. And on early trying, it seems to me to be a way more speedy and convenient way of navigating the Mac than using Finder windows. I am actually looking forward to seeing how this may easy my daily work. If I was, say, a writer, it would be different, but being an editor and webmaster, handling hundreds of photos in various ways every day, I do a lot of navigating in the file hierarchy and handling of files.
Here's a couple of examples: I right-click on the desktop, and I have access to a menu-system which can quickly lead me anywhere on my disks. When I have found a file I am interested in, I can press Q to get a "quickview" of it. Or I can press G to grab the file and drag it out! Kewl. Very fast. Free from much of the opening and closing of folders.
I couldn't find out how to see the previews while I had the menu, so I asked the creator. He said:
On 10.4 and 10.5 systems, pressing cmd-opt-shift while mousing over a FinderPop menu item will momentarily pop up a Preview window.
If you're on 10.6 Snow Leopard, this only works when you control-click the menubar. I haven't ported that Preview code to Cocoa yet so it won't work in the Snow Leopard Finder. --turly