This is a snippet from here:
http://www.helium.com/items/1501505-highest-scoring-scrabble-word
In October of 2006, Michael Cresta set a new world record for the highest scoring Scrabble word:
QUIXOTRY, 365 points. During the same game, Cresta reached a record breaking 830 total points by one player in a single game. When combined with the total score of his opponent, Wayne Yorra, the game also reached a record 1,320 points in a single game!
How is it possible to earn 365 points on a single word? QUIXOTRY was a once in a lifetime play. To begin, the Q and X are two of the highest scoring Scrabble tiles. QUIXOTRY is also an eight letter word, created by using all seven of the players tiles, earning him a 50 point bonus. Finally, the word was played on not one, but two triple-word bonus squares!
In Scrabble, having a word that spans across two triple-word bonus squares is known as a triple-triple. Triple-triples are rather rare. They can only be made with an eight letter word (known as a bingo) and are worth nine times the word's total score, plus the 50 point bonus for using all of the player's tiles in a single word.
Also look here:
http://www.fun-with-words.com/scrabble.html