A2zWords: Jamble Search (help)
Rack Letters  Uppercase= Required?
Word Pattern Match Where  
Min. Length   Sort By Score Length Alphabetical

Enter the letters from your Scrabble rack in Rack Letters box.  Use the '#' character for blank tiles.  To interlock with words already on the game board, input an optional Word Pattern using '_' characters for empty spaces on the board.  The other options can be used to refine the search (See Help).