Across and Across Lite: Literate Systems' crossword display and construction software. [Windows, MacOS, Linux]
Arensus Crossword Puzzle Editor: Tool for creating and publishing crosswords. [Windows]
EclipseCrossword: Creates crosswords and puzzles, includes project ideas, examples, tutorials and international applets.
Henry Casson's Crossword Utility: Enables a crossword grid to be entered and converted to and from a text encoding which can be emailed. Freeware. [Windows]