Apple's .Mac Service
Among many other benefits, Apple's .Mac service provides a 100 MB iDisk which is accessed over the Internet. It's ideal for backups of important files, sharing pictures or home movies with friends, or even keeping files synchronized between multiple computers. In Panther, you can access or make changes to a local copy of the iDisk even when disconnected from the Internet. When Internet access is re-established, the iDisk on the Internet is automatically updated if necessary.