By teaching kids how to attribute when they borrow or amend an image or music you are teaching them how to reference from a very young age. I can promise you their uni lecturers will thank you in the long run!
Adding music and images to a piece of writing broadens a students ability to express and also levels the playing field a little. No longer do those students who excel in writing rule the roost, students with a flare for images or a flare for music have just as much of a chance to express themselves powerfully. I had my students write a 'feelings' poem. I've been doing this for years, however the year I added imagery and music to the lesson was the most powerful.
A student writes I feel .... then needs to find or make an image to illustrate that feeling, then needs to find a sound effect or music to illustrate that feeling. Now that is a lot of learning out of something that was once a quick way to write a poem. Add on top of that a public performance by critiquing amongst peers or putting it on the web and you have a truly powerful learning experience which adds motivation by the truck load.
Every step in this lesson has a breadth of learning. It is not narrow by any means of the imagination and that is what I love - deep, broad embracing of language. By language I mean the way we communicate and let's face it, we very rarely communicate solely through writing.
I'm gathering up some resources to share. Feel free to take a look and add some more that you know of :)