This Dashboard Widget gives you speedy access to clues for finishing your crossword. Enter the letters you have and the ones you don't to get a list of words that could fit.
A French user has been kind enough to provide a French dictionary. He says it is "the latest Official French Scrabble dictionary and is public domain". Uncompress the download and then in XwordLookup, click the little i in the bottom right corner to change the path of the dictionary file. For example, if you put the uncompressed file, odsLower, in your home directory, change the path to "/Users/yourname/odsLower".