Were you able to see it in FW Target Mode?
Some ideas...
Either boot this one in Target mode...
http://support.apple.com/kb/HT1661
And recovering from another Mac, or booting this Mac from another HDD, then using Data Rescue...
http://software.bigbigsoft.com/data-recovery-mac
(Has a Free Demo to see if it could or not, but you'll need another drive to recover to).
rccharles on file recovery...
"Stellar Phoenix Macintosh - Mac data recovery software, recovers data from damaged, deleted, or corrupted volumes and even from initialized disks."
They have a trial version, so I guess you can see if your data can be recovered...
http://www.stellarinfo.com/mac-data-recovery.htm
FileSalvage is an extremely powerful Macintosh application for exploring and recovering deleted files from a drive or volume. FileSalvage is designed to restore files that have:
* been accidentally deleted.
* become unreadable due to media faults.
* been stored on a drive before it was re-initialized/formatted.
http://subrosasoft.com/OSXSoftware/index.php?main_page=product_info&products_id= 1
http://discussions.apple.com/thread.jspa?messageID=11073082#11073082
DiskWarrior from Alsoft...
http://www.alsoft.com/DiskWarrior/
Using Scavenge mode.