There's also Chambers Crossword Solver, which I have as a book. Very useful when you have alternate letters.
e.g. go to the section for 11 letters, look up S-I-K-R-N-E, and lo and behold Snickersnee, as well as any other words with that combination. Alternatively, there now seems to be available Chambers Pocket Version Crossword Dictionary, an electronic gadget. You enter the number of letters, eg 11, fill in the letters that you know , or ? for those you don't know, press ENTER, and up come the possibilities. I don't doubt that it, or Lexibook, which is similar, is well used by many A/Bers. Not a bad thing for someone to give you as a Christmas present.