Free software:

a) Amanda, or the Advanced Maryland Automatic Network Disk Archiver is the leading Open-Source computer archiving tool that is able to backup data via a network.

b) Dump is a unix program used to backup file systems. It's one of the oldest around and there are benchmarks indicating it's one of the best too.

c) Rsync is a computer program which synchronises files and directories from one location to another while minimizing data transfer using delta encoding when appropriate.

Proprietary software:

a) Acronis is a technology company producing file system-related software tools, backup and restore etc.

b) VWSI or VisionWorks Solutions Inc is a software company most well known for their software: File Access Manager & Vision Backup.