dd_rhelp is a shell script that calls dd_rescue. dd_rescue does a block level copy, and basically doesn't take no for an answer; if it can't read something, it writes 0s instead. dd_rhelp sets it up so that if it encounters a bad block, it moves that block to the end of the process, and skips to the next good block. When I tried to run dd_rescue yesterday, it got caught at 7 GB of data, and pretty much tanked overnight. I think it wrote about a gig of 0s before I stopped it. dd_rhelp actually managed to get the whole drive with no errors (!) I have no idea how.
Oh yeah, it's also GPL (ie, free)
