Puzzle Workshop is a program for the automated compiling of crosswords. It comes in two flavours:

Version 1

This is free, a demo can be downloaded from this site. It compiles freeform crosswords only, click here for the Version 1 pages.

Version 2

This does everything that Version 1 does, but can additionally create symmetrical, newspaper-style crosswords from a built-in dictionary, and can combine your own word list with dictionary words. It can be purchased for £12.