Disk Warrior is for sure a software that one would like not to use, but one should always have in stock. Indeed, its main feature is to recover directories and structure from a HD with a logical failure; something for which Apple Disk Utility can not help.
Disk Warrior v4 is released and brings support for MacIntel, while enhancing data recovery features.
Please remember that it is a rescue solution, and should not in any case be considered as a backup solution Making a copy of your data is something you should always do regularly.
It costs 99.95$ or 49.95$ for the update; it might be considered expensive by some users, but it might also allow you to recover invaluable data from a dying HD.
Direct link to the official website:
http://www.alsoft.com/DiskWarrior/details.html