Golan Levin, Double-Taker (Snout), 2008. Similar concept as the Senster, revised technology and different attitude. http://www.flong.com/projects/snout/
Toshio Iwai, Composition on the Table (shown at Siggraph in 1999, which I think is the year of its creation, video is from 2009). http://www.youtube.com/watch?v=paETniSX7OQ
This diagram made everything clear to me: http://xkcd.com/730/
A very good short article on ten different ways to use magnets with sensors: http://archives.sensorsmag.com/articles/0397/mar_mag/index.htm. I especially like the magnetic push-button, that does away with the need for springs.
Spencer Finch, 2 hours, 2 minutes, 2 seconds (wind at Walden Pond, March 12, 2007), 2007. http://www.spencerfinch.com/view/mixed-media/75
Edward Ihnatowicz, The Senster, 1970. http://www.senster.com/ihnatowicz/senster/index.htm
Golan Levin, Double-Taker (Snout), 2008. Similar concept as the Senster, revised technology and different attitude. http://www.flong.com/projects/snout/
Toshio Iwai, Composition on the Table (shown at Siggraph in 1999, which I think is the year of its creation, video is from 2009). http://www.youtube.com/watch?v=paETniSX7OQ
Haruo Ishii, Omnipresence (Hyperscratch), an installation with hundreds of chimes, shows up in this compilation video without the sound (!?): http://www.youtube.com/watch?v=paETniSX7OQ. Documentation on his web site, also silent, is helpful. http://www.land-net.co.jp/~stone/hyperscratch12/hs12.htm.