You can use the command line to work with disk images and backups, without any extra software.
sudo dd if=/dev/hda1 of=/home/hda1.bin
Or for a compressed disk image:
sudo dd if=/dev/hda1 | gzip > /home/hda1.bin.gz
sudo dd if=/dev/hda of=/home/hda.boot.mbr bs=512 count=1
Restore MBR (from a Live CD)
sudo dd if=/mnt/hda1/home/hda.boot.mbr of=/dev/hda bs=512 count=1
sudo dd if=/dev/hda of=/dev/hdb conv=noerror,sync bs=4k
Assuming your USB stick is /dev/sdb, don't use the partition (/dev/sdb1):
sudo dd if=Ubuntu.iso of=/dev/sdb