Killer Word

Killer Word is a deadly dictionary app which finds the word you need to win at word games like Letterpress.  

Can't think of a word with a Q but no U? No problem - here are 75 of them. Need a word with K, V, M & H to finish the game? No problem - it knows 9 obscure words that match.

Just tell it the letters that are essential and it lists all the words that feature those letters anywhere. Then narrow the list down by also telling it the letters you don't want, i.e. if there is no E or A on the board, just subtract all those words out.  

It lets you show the matching words by either standard alphabetical order or by length, which is very useful since the shorter words are more likely to be possible on the board.