An experimental jQuery widget.
To do list:
You can see a demo here.
It's based on a Facebook/Apple Mail-style interface.
Unfortunately other projects have taken the forefront for now. I'd like to do more work on this, perhaps by hooking in an existing autocomplete plugin, and reworking the code a bit. However, at the moment, there are no immediate plans to continue development.
Please contact me if you would like more information.