"http://www.wondershare.com/disk-utility/recover-trash-mac.html
Wondershare Mac Data Recovery - Accidentally deleted important files by emptying Trash Bin? You can still recover them from your Mac actually. Here tells why and how to recover Trash Mac.
http://www.wondershare.com/data-recovery-mac/
Are files gone permanently after emptying Trash Bin?

When we emptied Trash Bin (excluding secure emptying), what we actually deleted is not the file itself. The operating system simply loses the access of the file, as the pointers between files and file system index are deleted. The space occupied by deleted files is marked as ""available to reuse"", so the deleted files remain physically intact on the drive until they are overwritten by other files. The files will be only deleted when they are overwritten by new files. In order to prevent overwriting we need to stop using the Mac immediately if we want to recover deleted files from Trash."