When you've got a folder in the dock, and you want to drag an item into that folder, does anybody else find it disconcerting to have that folder MOVE OUT OF THE WAY for a second because it thinks you're trying to add something to the DOCK instead of to that folder?
Well, my absolute favorite Mac OS X tip is if you hold down the COMMAND key when you drag an item to a folder in the dock, the folder will NOT slide out of the way -- it will just sit there waiting for you to drag stuff into it!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020307214711269