I have 2 answers.
1) A speaker similar to the X-LS, except front ported. Because then I could put a "bookshelf" speaker on a bookshelf, or wall mount it.
2) A way to integrate digital music libraries (mp3, etc.) into your main audio system that meets all 3 things: inexpensive, easy to use, high fidelity. Because existing devices do 2 out of 3, at best.