WinDataReflector portable is a free file synchronization and backup software tool. It can be used to create backups and synchronize file and folder contents.
ZBack is a Portable Free Backup Utility and Synchronization Software created by David Zorc, Zagreb, Croatia. It can be used to synchronize, mirror or backup directories, files or entire drives.
Drive Image XML is Free Backup Software. This portable backup utility can be used to create a backup image of a partition or logical drive or (clone) copy directly from one drive to another.
IdleBackup is a Portable Free Auto Backup Software utility. It can be used to mirror or automatically backup folders, files or even entire drives on a set schedule or manually.