Tool - Sober (played as a lullaby from a compilation series that does that kind of thing to stuff, I bought Bjork and a friend bought NIN for his kid).
Oddly works really well and I think it is an interesting way to show people what I see in some of the stranger musics I like by showing it on far more standardised instrumentation (Glockenspiels, Vibraphones and whatnot is a bit easier to stomach). Wouldn't work for all of it (Aphex Twin on a Glockenspiel?), but it is alright for Bjork without her uh unique singing style and good for Tool without the guitar drones and lyrical content.
Yes I bought a CD for babies.