Images found at:

http://www.eyesontutorials.com/articles/47/1/Magic-Book

http://www.thousandsketches.com/blog/?p=326

http://www.sgxmusic.com/

http://astro.uchicago.edu/cara/vtour/pole/dome/pix/
http://astro.uchicago.edu/cara/vtour/pole/dome/pix/tunnel.gif

http://www.doom3world.org/phpbb2/viewtopic.php?f=57&t=8964&start=20
http://www.plainsfolk.com/seminar/weblog/Stormy%20Fargo%20Sky.jpg