Quackle is a free crossword game, artificial intelligence and analysis tool.
Elise is another free crossword game, artificial intelligence and analysis tool.
Zyzzyva is a free word study program available on a number of platforms.
CSWcheck is a text-based program, designed to be used for adjudicating plays at Scrabble tournaments. It runs on Windows and MacOS X. This version is loaded with the Collins Official Scrabble Words List, third edition (informally known as CSW12). This word list will become official for play in ABSP tournaments from 1 January 2012. See the readme.txt file included with the program for more details.
• CSWcheck for Windows
• CSWcheck for MacOS X