Henry Lim, a musician and Lego-fanatic, build himself an instrument. From his page you can see that he already was doing 2d pictures, and even a full size statue of Queen Amidala , but this time he started out building a Grand piano. Due to the enormous amount of pressure a grand piano takes from the tension of 88 strings he figured a Harpsichord would be a more reasonable goal.
Lego-Hammond organ (easy because it is just the case, the rest is electrical)
Check his page for more pictures, the whole production process and audio-clips of the instrument.