From Shinkuro:
Use the Shinkuro software to share files across enterprise boundaries – securely. Just install the software on each machine, create a group and designate a folder you would like to share with the group. Any files you put in that folder will be shared with the other members automatically.
Shinkuro also includes secure instant messaging and secure screen sharing, to give you a complete collaboration environment. Shinkuro’s lightweight technology works easily with all of your applications.
Shinkuro runs on Windows 2000 and XP, Mac OS X “Panther”, Linux, and FreeBSD.