Seeing as that the most recent of the iPods have ludicrous amounts of memory, and can play videos etc, why not get a nice little slideshow of pictures that you can attach to a specific song or album for whenever you play it?
You get your pictures off of a digital camera, off the internet, etc, put
them in a folder, and 'attach' certain pictures to a song (very much like the cover art of the album). So let's say that you have your pictures from a holiday in France, and all holiday you were listening to Green Day's American Idiot album. You get your holiday pictures and 'attach' them, (by dragging and dropping, most likely) into the album's specific folder, then update your iPod. So now, when you start hearing the begining lyrics to 'Jesus of Suburbia', you'll get a mini-slideshow of your holiday photographs.
This could also work for audiobooks, as you could insert screenshots of its reciprocating movie to the chapters (if it has a movie).