SystemRescueCd

This is a good one... I've used it since it was only a Command line version. Now it has a GUI too...

About SystemRescueCd

Description: SystemRescueCd is a Linux system rescue disk available as a bootable CD-ROM or USB stick for administrating or repairing your system and data after a crash. It aims to provide an easy way to carry out admin tasks on your computer, such as creating and editing the partitions of the hard disk. It comes with a lot of linux software such as system tools (parted, partimage, fstools, ...) and basic tools (editors, midnight commander, network tools). It requires no installation since you just have to boot on the CD-ROM. It can be used to perform admin tasks on both linux servers, linux desktops or windows boxes. The kernel supports most of the important file systems (ext2/ext3/ext4, reiserfs, reiser4, btrfs, xfs, jfs, vfat, ntfs, iso9660), as well as network filesystems (samba and nfs).

Read more...
http://www.sysresccd.org/Main_Page

Don