Finally the Chaucery site has its first authentic AJAX application, Instant Crossword Tools. There are other sites that provide anagrams and complete words with missing letters, but in testing I've found it quicker, easier and more fun to use my instant version.
The two main differentiators between different online crossword tools are (a) their ease of use, and (b) their wordlists. I'm pretty sure that I have the first one covered, with the instant results to the users' queries a vast improvement on the button clicking and page loading that people used to have to suffer.
For my word list I originally used a combination from Grady Ward's Moby lexicon project. In particular, I merged the two scrabble word lists with the common dictionary word list, and got a pretty comprehensive result. However, in testing I found that certain plurals were missing. As adding plurals algorithmically is not feasible, I instead switched to Ross Beresford's UK Advanced Cryptics Dictionary, which seemed eminently suitable.
The end result is a tool that I hope will be useful to anyone interested in words, but especially to those setting or solving word puzzles.