copying a disk image to restore on linux

[phani () myrealbox com]

hi all,
   I would like to know if there are any utilities on linux (preferably freeware) which can create a complete image of 
the hard-drive. I know dd exists, but that would create the image of the entire drive. If the drive was (say) 40 GB and 
the free space is 20 GB then that would be a waste of space. Is there a tool which would let me create the image of the 
used space on the drive ?

thank you
gangadhar