Spring loaded folders - I liked these in OS 9, but I haven't really felt their absence in Mac OS X because I've gotten out of the habit of throwing stuff on the desktop. I haven't tried this, but if dropping stuff on the big Finder buttons worked, that'd be helpful.
Shaded current app - I would like to see this one. Seems like a natural thing to do.
Custom Hilight Colors - I don't think this will happen without a _reason_ other than simple aesthetics being given. Either due to marketing pressures or user interface designers, I think they are going to stick with blue. My guess is because it's a very calm, non-computerish color. Indeed the special effects guys in the Matrix did a lot of work to remove the color blue from as much of the matrix scenes as possible to give it a bleaker, sterile, computerish feel. Blue seems to be Apple's color for now.
Windowshade - I'm ambivalent about whether it returns or not. It was only useful to me for reading something that was right behind it and then immediately opening it back up again. Since all the titlebars were in almost the exact same place, it was hard to deal with if you brought other windows to the front (to scroll for example) and then needed to unshade the first window. I'd end up dragging a bunch of Windows about 20 pixels diagonally from each other to try and find the one I was looking for. Grrr.
A few of suggestions that I'd like:
Movable focus - In Java apps and MS Windows, it's possible to control almost all of the user interface from the keyboard. Part of this comes from being able to use a key to change the "default" button or input area. It'd be nice to be able to move the "pulsing blue button hilight" to different buttons and sliders just by tabbing.
Better Drag & Drop - Scrapbook is gone. The NeXT shelf is gone. They try to get you not to use the desktop if possible. How are we supposed to organize and easilly access our clipping files? The dock is the answer I suppose, but I'd like a separate app that's easy to drag into, search on, and drag out of.
Terminal - I know that it's included in the public beta, but I think that people should say "Thanks" and encourage them to keep it in.