Great as Mac OSX is i do miss the old Finder and UI from pre-OSX Mac days (and even then look of the pre-System 8 days still can't be beat). Of course pre-Mac OSX crashed a lot, didn't have very good multitasking and less toys than OSX but some charm and fun was lost when Apple transitioned. I miss the days of trying a funky extension (remember the one that rendered your desktop in ASCII characters?) and Resedit to do weird (and dangerous things) to your Mac.
Displaperture.app to give my desktop rounded edges, as Steve insisted rounded rectangles are everywhere ok?
Another thing is to use a retro wallpaper. I used to like the green tartan wallpaper, luckily some other people had a yearning for the old wallpapers too and they are available to download. Now all i need is Chooser and i will be in retro-Mac hog heaven.