I've been working on a website which provides an environment and tools for crossword construction requiring no installation or special hardware. Its focus is collaboration, and I have already started a test in which anyone is welcome to participate. The site is http://crosswordcomposer.com
and I have started a Google group for discussions which is http://groups.google.com/group/crosswordcomposer
You can load and save to/from XPF and .puz, and it supports a nice print format. It's brand new, so please be patient and let me know what you think!