The Dock's Stacks feature lets Leopard users view a folder's worth of stuff with one click. You'll either love it or hate it, use it or not. If you do use it, here's a little tip that improves it slightly (in my opinion).
When you've got a bunch of files from a Stack displayed in Grid View, it can be hard to spot the particular one you're looking for, especially if many of them look identical (such a collection of text files or word processor documents).
Luckily, there's a highlight you can switch on, that puts a whiter background around the file you're mousing over. It makes it slightly easier to ensure you click on the correct file.
The highlight appears normally if you use the arrow keys to move around a Grid, or if you type Command and the first letter of one of the files displayed. But this trick switches it on permanently, so that it is always in action whether or not you use these keyboard shortcuts.
Read on for all the commands.
Switching the highlight on and off is easy. You can either type a short pair of commands command into Terminal:
defaults write com.apple.dock mouse-over-hilte-stack -boolean yes
(Repeat that with "no" instead of "yes" to put things back the way they were.)
Or, if you'd rather stay away from Terminal, use Alcor's Secrets prefpane to switch it on and off (go to Dock, and check "Hightlight stack items on hover"). Secrets does come with some warnings that you could break things terribly if you're not careful, which is true. But you'll be careful, won't you?