As a house rule (since none of us have any plans to ever competitively play Scrabble), the list of all legal two-letter words which came in our "deluxe Scrabble" instruction manual is available to all players at all times.
It has really helped cut down on the number of games where we get stuck or frustrated because there's "nowhere to move", both by making more moves legal, and helping us keep the board configuration more compact, while at the same time eliminating what we see as trivia (what 2-letter words are legal) vs. "regular English" in the games we play.
one of the world's largest tournaments, the annual king's cup tournament in bangkok, actually supplies 2, 3 and selected 4 letter word cheat sheets to all the players, to compensate for the fact that thai players use the north american rather than the world dictionary.
It has really helped cut down on the number of games where we get stuck or frustrated because there's "nowhere to move", both by making more moves legal, and helping us keep the board configuration more compact, while at the same time eliminating what we see as trivia (what 2-letter words are legal) vs. "regular English" in the games we play.