One of the things that used to bug me was when I was trying to drag a picture off the web for depositing in my desktop pictures (for the site) folder invariably the browser window would hide the pictures folder when I tried to drop it into the desktop folder and you then had to wait until it sort of sprung open.
Using Expose (press F3) however now organises all open windows into a tidy grid and you can then drop it into the required folder nae probs, as they say. Wish I’d known about this 2 years ago.
Mind you, I still can’t see any good reason to use Spaces on my mac. That programme baffles me.