Note: moveAddict is no longer being actively developed.
moveAddict provides a functionality the Finder was missing, the ability to move files using the keyboard. It's meant to replace dragging and dropping for anyone that would rather use the keyboard instead of the mouse.
In a nutshell, you can use it to cut files or folders and then paste them where you want.
As a bonus, you can also use it to merge folders instead of completely replacing them, another functionality that the Finder was missing.
For anyone that hasn't used cut and paste for files before, here's a short description:
Cut - when you cut files the only thing that happens is that moveAddict remembers the location of the files, it does not change the files in any way
Paste - when you paste, moveAddict moves the files from their original locations to the new one
If you cut a file and forget to paste it, nothing happens!
moveAddict does not change the system or the Finder in any way, it's just a regular application which you can uninstall by deleting it.