One way to prevent earbud tangling is to make the cord thicker, and AT wrote about achieving this through string-knotting à la preteen summer friendship bracelets.
I did this project today and LOVE, LOVE, LOVE the way it came out. This would be appropriate for preteens and up, or that precocious young crafter who's already into friendship bracelets. Also could be used to make a unique, cheap gift for a friend or sibling.
Read the full tutorial on my blog here.