Biggest tsunami ever recorded was in Lituya Bay, Alaska, it's height - astonishing 524 meters (1724 ft.)
On July 9, 1958, an earthquake of magnitude 7.7 (on the Richter scale), caused 90 million tonnes of rock and ice to drop into the deep water at the head of Lituya Bay. The block fell almost vertically and hit the water with sufficient force to create a wave approximately 524 meters high (1,724 feet).
Artist depiction of a megatsunami from "The Day After Tomorrow"
The wave didn't travel far, as it struck land almost immediately. Two people fishing in the bay were killed, but another boat amazingly managed to ride the wave. Scientists named these waves megatsunami1.
On a related note - this friday (11/03/2011) most populated regions in Japan were torn by the biggest earthquake in its recorded history, massive tsunami waves and aftershocks have caused tragedy that Japan will remember for generation to come. Many have been killed or are unaccounted for. Support them if you can and share this information with your family and friends.