I use a cookbook stand to hold books open, since I'm still in the early stages of learning I have a few "beginner" books that I'm working through and some exercise books. The TV tray easily holds the book stand, my tuner, pick container, pencil, highlighter, etc. Later I'll pick up a dedicated music stand but will probably still keep the tray out to hold extra stuff.

They're also items that are useful for more than just music practice (in case the person learning decides to stop learning).