You may have noticed, after OS X updated to 10.6 Snow Leoaprd, that you could undelete items from the Trash using the Finder's "Put Back" context menu item. Here's how to do that with a keyboard shortcut.
Every once in a while, you delete something you end up needing later. If you want to move something from the Trash back to its original location, you can right-click on it and hit "Put Back". It turns out, there's also a keyboard shortcut for this feature, but it's about the last one you'd think of: Cmd+Backspace.
That's right, the keyboard shortcut to undelete it is the same keyboard shortcut you use to delete things from the Finder. In retrospect, it kind of makes sense, but it's something we would have never thought to try on our own. So, if you like to use the Trash as a "pre-deletion" receptacle and end up putting a lot of things back, this should help speed up the process a bit.
Undelete from Trash to Original Locations [Mac OS X Hints]