Disk dumps (dd) over the network (netcat)
On the receiving machine (booted from live CD or similarly inactive partition sda):
netcat -l -p 4778 | dd of=/dev/sda
On the sending machine (booted from live CD or similarly inactive partition sdb):
dd if=/dev/sdb | netcat 192.168.0.4 4778
(-l listen; -p port)