Multiplayer Zelda doesn't interest me in the slightest, but the concerts and audio CDs are pretty cool I suppose, but I would have loved something a bit more substantial.
Imagine an 'Art of the Legend of Zelda' book they could have put together and published. It could have been filled with sketches, concept drawings, illustrations, renders etc from the last 25 years, plus plenty of insight into the art styles of each Zelda game. How amazing would that have been?
Obviously it would have been a decent amount of work to put together so probably too much hassle for Nintendo but I'd have gladly paid money (and lots of it) for something like that.