VirtualBox:
VBoxManage modifyhd [name].vdi --resize [dimension in Mb]
eg. VBoxManage modifyhd test.vdi --resize 80000
Commands:
umount [partition]
e2fsck -f [device - /dev/sd*]
resize2fs [device - /dev/sd*] (with no parameters, all the free space)
(parted -> print list or fdisk -l)
eg.
umount /home
e2fsck -f /dev/sda6
resize2fs /dev/sda6