Grouper is a Peer-2-Peer application that I Beta tested. Grouper allows a user to join or create a group, and share files within that private sector. It allows streaming of your MP3 or WMA files over the internet to other users. It became useful to some as a medium to share their home music libraries over long distances to portable devices, such as laptops.
Grouper sent me a Grouper T-Shirt for helping Beta test. Henceforth, however, I have lost interest in Grouper, and haven't participated in any Beta testing or support.