http://www.mrsec.wisc.edu/edetc/MFM.html
Refrigerator Magnets have a complex and ingenious magnetic structure, according to a Web site from the nanostructured materials and interfaces group at the University of Wisconsin—Madison. The magnets are educational, too. The Madison group uses the devices in lab demonstrations of such physical phenomena as self-assembly, salt cleavage, metal deformation, and magnetic force microscopy.

http://www.bekkoame.or.jp/~khirata/indexe.htm
Japanese naval engineer Koichi Hirata’s job and hobby is the Stirling Engine, a fuel-efficient method for converting thermal to mechanical energy that was invented in 1816 by a Scottish minister named Robert Stirling. Hirata’s comprehensive site contains tutorials on the operating principles of the Stirling engine, a gallery of working engines, instructions on building your own engine, and descriptions of the more than 40 model engines that he has built.

http://www.phys.unsw.edu.au/music/flute
On their Web site Flute Acoustics, acousticians John Smith, John Tann, and Joe Wolfe of the University of New South Wales describe how a flute produces sound. The site offers not only general information about musical acoustics, but also, for each of the standard flute fingerings, the corresponding sound and impedance spectra and an audio file of the note.