Backup utilities are useful software which provides you with a tool to make sure your selected important data is always copied to a safe location. Why is backup important? Suppose your computer crashes with all your contacts' list or something even more important. How do you get hem back? The backup software enables you to make timely copies of the important files and store them to an external location.
Amanda Backup and Recovery Software Community Edition - Backup Utilitiy
This one is for Linux users and is open source. This one uses a single computer to act as a focal point for backup of several other computers on just one single medium.
Back4Win - Backup Utilitiy
This one is good as it enables you to backup to zipped files or self-extracting compressed executable. It also features multiple compression levels, disk spanning, burning to CD-ROMs with passwords on the backups and moreover can repair damaged backups.
BackupPC Open Source Backup (Internet Connection Needed) - Backup Utilitiy
This utility allows you to backup your important files to a remote server for storage. The program is open source and is cross-platform. It runs on Windows, Linux and Mac OS X.
This one is nearly the same as Back4Win with backup to zipped files or self-extracting compressed executable. It also features multiple compression levels, disk spanning, burning to CD-ROMs with passwords on the backups and moreover can repair damaged backups. Additionally it also has backup to remote server and FTP backup.
From Freebyte: Freebyte Backup is a very effective freeware backup program for Windows. It enables you to easily backup files from any amount of directories and sub-directories. Freebyte Backup can backup all files, or a selection of files: you can filter according to file-date, file-type and even perform an incremental backup. Also: support for profiles. Small, simple to use, and simple to install (no dll's!!).
Microsoft SyncToy - Backup Utilitiy
This software, is not really a backup software but is a data synchronization software which enables you to keep the sames version of files at two different locations. It even detects things like renaming of files and others. However the hugest limitation of this software is that it runs on only Windows XP SP 2 with the .NET framework and Windows Vista.
Unison File Synchronizer - Backup Utilitiy
Just something like the one above except that it is on a network and is cross-platform. Synchronizes multiple hosts across the Internet. It is released under the license of GNU GPL and runs on Windows, Linux, Solaris, MAC OS X.