In Panther's Preview App, you can drag images from the side drawer and drop onto Apps, Dock icons and other windows, folders, the desktop. Anything you can do with the original file. This is useful for checking a CD or folder of images before using Photoshop.
Don't have Jag any more so can't check if this is new, but I think it is.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031127083420943