Best Free Disk & File Tools for Linux

Drive Imaging Program

Clonezilla: Saves and restores only used blocks in the harddisk and increases the close efficiency. The version of Clonezilla Live is suitable for single machine backup and restore.
G4U ("Ghosting for Unix"): "Not only can it clone disk to disk (any size) and copy disk partitions, it can also create and restore image files both locally and from an FTP site, if the workstation is connected to a wired network with a DCHP service."

File Manager

Dolphin: A file manager for KDE (by default) and good for other desktop environments such as GNOME as well, focusing on usability with navigation bar, view properties, split of views, dockable panels and many other useful features.

Folder Synchronization Utility

FreeFileSync: "Very clear and informative interface, file collisions and deletions are readily recognizable. If you require a sync program that can copy files that are in use or locked, it has you covered there too!"

File Archiver / Zip Utilities

PeaZip: "Easy to use and very versatile, capable of creating 7Z, ARC, BZ2, GZ, PAQ/ZPAQ, PEA, QUAD/BALZ, TAR, UPX, ZIP files and extracting from 98 archive types."
File Roller and Ark, both archive managers designed respectively for GNOME and KDE desktop environments to create archives, view or extract files from archives, work as front-ends to command-line archivers supporting various file formats.

Partition Manager

GParted: "a GNOME partition editor for resizing (enlarging or shrinking), creating or deleting, moving or copying partitions on a hard disk, creating a partition table, enabling or disabling partition flags such as boot and hidden."
Parted Magic: "Employs core programs of GParted and GNU Parted to handle partitioning tasks and can be run from a live CD, DVD or USB flash drive."
TestDisk: "A console application designed for data recovery. It can be used to fix partition table, recover deleted partitions or copy files from deleted partitions."

Secure Erase Utility

Darik's Boot and Nuke: "Constructs a floppy disk or CD that will automatically wipe the hard drives of any PC that's booted from the disk, great for bulk disk cleaning and emergency."

File Encryption Utility

TrueCrypt: "Powerful, flexible and highly-effective encryption program to encrypt files, folders or entire drives. Use this seasoned, widely-used encryption program when you want an encrypted container that mounts as a virtual drive."

CD Recovery Utility

Dvdisaster: "A preventive program to create an error correction file from a good CD or DVD for data recovery."

Online Backup Sites

Dropbox: "Provides 2 GB free space for backing up and sharing your files, works similar to any other folder of your computer—after installation, simply drag and drop files/folders to Dropbox you want to backup, share or sync with other computer."

File Copy Utility