http://www.coastal.udel.edu/faculty/rad/linearplot.html water waves

http://www.ngsir.netfirms.com/englishhtm/Interference.htm lots of applets

http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html wave demos

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=16 reflection and refraction

http://www.geocities.com/capecanaveral/hall/6645/propagation/propagation.html same as above

http://www.abdn.ac.uk/physics/ntnujava/waterSurface/waterSurface.html another water surface one

http://library.thinkquest.org/19537/java/Wave.html really nice sound wave

http://illuminations.nctm.org/tools/soundwave/ excessively cool sound wave

http://www.udel.edu/idsardi/sinewave/sinewave.html simply about waveforms

http://www.kettering.edu/~drussell/demos.html numerous wave demos really good

http://www.physics.smu.edu/~olness/www/05fall1320/applet/pipe-waves.html standing waves in a pipe

http://pdgusers.lbl.gov/~aerzber/aps_waves.html guide to lots of applets

http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/index.html lots of great simple stuff