Integrate a friends list.
-The names of your friends and the names of their games are highlighted.
-Have a single page where you can see all of your friends and their status (perhaps their score, if global score is added)
-Have a single page where you can compare your accomplishments (longest word, etc) with that of your friends.
-Have a message go out to your friends whenever you have beaten their record.
-Be able to wager (not all but some) extra "score" per game with your friends (if global score is added)
-Treat disconnects nicely. Save and easily restore the game between friends.
And perhaps add more features that you can think of as benefits of being a friend, that you felt iffy to add between complete strangers. And I don't have any data but I'd say that a good chunk of the people who play PyScrabble know each other already and would have no problems with registering as "friends".