Yesterday, Greg and I took in a gamelan concert up at Bowdoin College. One of his grad-school classmates belongs to a gamelan group in Cambridge called Gamelan Galak Tika, and they were in town to play with a Balinese composer who was doing a residence at Bowdoin.
Everything I know about gamelan would fit into a miniature thimble without danger of overflowing, but it's fascinating stuff -- very complex and shimmery. It's a form of music native to Bali, sometimes accompanied by dancers in gorgeous silks and traditional headdresses. The music is remarkable in many ways -- including the fact that almost all of the instruments used are basically tuned percussion, mostly metal, with the bass line provided by gongs, and rhythm by hand drums and cymbals. The instruments are all deliberately tuned slightly differently, which makes them sound a little out of tune to Western, equal-temperament-trained ears. The difference in tuning causes the sound waves to "beat" against each other, and that effect produces the "shimmery" effect of the music. Apparently, this also causes the music to be audible from many miles when performed outdoors.
Anyway, I really enjoyed the entire concert, and the group graciously allowed the audience to come up and play the instruments afterward. Greg and I explored the chords you could create with the instruments in the different pitches, and he was pleased that you could form a few seventh and ninth chords with the right combinations. I had to play the bass gong, just once.