For the most recent tsunami (starting around Sumatra) I calculated the wavelength
as 2700km from the period, 30 min and the speed of siesmic waves thru sea water
The solution to the differential equation to the speed of water waves is complicated, but the hyperbolic tangent can be simplified when wavelenght>> depth leading to an interesting solution that the Tsunami speed is equal to the square root of g times depth.
This gives about 173m/s for the Bay of Bengal but appraoches 0 close to shore.
Thus the waves all catch up with each other at shore and form that wall of water, but in deep water the Tsunami is not very noticeable, only a few inches to a foot high. Note that none of the actual water near the Earthquake was transfered to Sumatra, Sri Lanka, etc. It was the energy that was transfered and the water acted as the medium for the wave
Great explanation of tsunami physics with simulations from University of Washington: http://www.geophys.washington.edu/tsunami/general/physics/physics.html
Explains difference between tsunami's and regular ocean waves: http://observe.arc.nasa.gov/nasa/exhibits/tsunami/tsun_physics.html
Great source of information from the New York Times on this last tsunami, including
hour by hour tracking of the tsunami and a simulated picture of Earth that shows
the wave as it comes out travels through the indian ocean: http://www.nytimes.com/packages/khtml/2004/12/26/international/20041227_QUAKE_FEATURE.html
This site also has pictures and data.
A simulation and wave height tracking of the most recent tsunami that started in Sumatra
A CNN article explaining the physics of tsunami's: http://www.cnn.com/2005/TECH/science/01/10/tsunami.height.ap/index.html
This site has before and after satellite pictures of the destruction from last tsunami: http://homepage.mac.com/demark/tsunami
Sites where one can donate money to help the cause:
Save the children