Mac: Sometimes you need a place to put a file temporarily while you clean up things elsewhere. Dropshelf gives you a temporary holding area to put files in so you can go about doing your business without worrying about organising them.
All you need to do is grab a file and drag it to the edge of your screen. Dropshelf will then hold the file for you until you need it. If that's too much work, you can also set specific corners of the screen to use, create an OS X Service, or set up a Hazel workflow to do it for you. Dropshelf is one of those handy apps that you don't need too often, but it's really useful when you do.
Dropshelf ($3.79) [Mac App Store]