Mac OS X Panther (10.3.3)
"Recovering an Initialized Drive
Peter J. Creath
Michael Bradley did exactly the right thing in disconnecting his drive and not touching it.
The best off-the-shelf (read: affordable) utility I have found for recovering Mac files is Data Rescue X. Unlike Norton, which progressively patches the drive it's trying to recover, Data Rescue X doesn't modify the drive to recover. It scans the entire drive looking for lost files and presents you with a list of files found. You can then recover those files to another drive. This does require another target drive, but it's by far the safest way for end-users to recover data from a zapped drive.
To be clear, even connecting your newly-initialized drive will modify it slightly (since the new volume will be automatically mounted), but those changes _should_ have minimal impact on your ability to recover your lost files. The ideal recovery process would be to make a forensic block-level copy of the zapped drive and do the recovery work on the copy.
Michael Bradley needs to get Prosoft's Data Rescue X. It takes forever and then some to run and do its thing, but is highly effective.
There is a demo available that will do the full scan (the part that takes hours and hours, even days sometimes) and show you what it found, but the demo will only recover 1 small file.
Having just gone through something similar with a client, I know exactly how Michael Bradley must be feeling. The good news is it is very much possible to recover the data in a situation like this.
The first thing to try is Prosoft Engineering's Data Rescue X software. It's quite capable of recovering data in this situation and is non-destructive (you have to have a second volume mounted which is capable of receiving any recovered data).
The other option (which is what we did) was send the drive to the guys at SoftRAID to have the partition map reconstructed by hand. It's not their normal line of business, but they were extremely gracious and able to restore everything for a fraction of the cost of a recovery at DriveSavers. They also offered to hand-deliver it to DriveSavers if they weren't able to restore everything. So don't lose hope."
There's more at the site. Wonderful discussion.