Since iTunes 9 (current version is 10.1.2) there has been a automated way of adding music and other iTunes compatible media into your library.
Probably the way most people do it now is simply drag a file or folder of music onto iTunes when it is running and the media is added.
Automate it for later!
However if you have a situation where you don’t want to sit there and drag a number of files or folders to iTunes (it can take some time if you’re adding a large number of files) there’s a little trick.
In your iTunes folder you will find a special sub-folder called “Automatically Add to iTunes” – if you place any iTunes compatible media (music, movies, PDFs etc.. ) the next time iTunes is run it will work through the folder and automatically add the media to your iTunes library.
True, it’s probably not going to be something that you’ll use all the time but I find it great when working between two computers on a network. I can access this folder across the network and copy any number of things into the folder without having to wait around for iTunes to do the importing.