If you folks have Leopard, then you should be using TimeMachine to safeguard against losing files to corruption or emptied trash. But if you have not yet installed Leopard, or are simply not using TimeMachine, and you find yourself wishing you could undelete an emptied trash item, you may be in luck.
The folks at SubRosaSoft have created a solid little application called FileSalvage ($79.00) which can retrieve files even after you’ve emptied the trash. When the trash is emptied, the OS X system doesn’t actually erase the data. Instead, it informs the file management system that the space previously occupied by the file is now available for being overwritten. FileSalvage can retrieve that file as long as the data for the file has not already been overwritten with other data. This is why it’s more likely that you’ll be successful in getting your file back if you use FileSalvage as soon after the file has been trashed as possible.
You can download a trial copy of FileSalvage and check whether or not your file is recoverable, then purchase the software to implement the recovery.
Check it out: FileSalvage