Zyzzyva is an invaluable study tool and word judge.
Quackle is a powerful world champion level piece of software with game analysis features.
There are also tools to look up words like ULU on Apple phones and Wordfinder on Android.
You can also play scrabble on the Mattel Scrabble App which you can connect through Facebook or email. Or the new Scrabblego App. which is really cool but very addictive.
There is also the ISC (Internet Scrabble Club) website