Home of dd_rescue is http://www.garloff.de/kurt/linux/ddrescue/
dd_rescue is your friend if you have to recover data from a crased harddrive. This tool will scratch all recoverable data out of your broken drive.
# standard run: dd_rescue input output
(rescue hard disk helper) - bash script to manage dd_rescue conveniently
Home of dd_rhelp is http://vaab.free.fr/utilities/dd_rhelp/index.en.html
In short, it'll use dd_rescue on your entire disc, but will try to gather the maximum valid data before trying for ages on badsectors. So if you leave dd_rhelp work for infinite time, it'll have the same effect as a simple dd_rescue. But because you might not have this infinite time (this could indeed take really long in some cases… ), dd_rhelp will jump over bad sectors and rescue valid data. In the long run, it'll parse all your device with dd_rescue.
For more details see its homepage …