Polytechnic Institute of New York University professor Nasir Memon has developed software that can reassemble deleted image files. The software uses file-carving techniques that restore the contents of a file after its identifying information has been lost or deleted. Although the software cannot recover partial images in which part of the original file has been overwritten by new data, "it will recover photos if all of the parts are still present on the storage medium, however scattered," Memon says. University of New Orleans professor Golden G. Richard III says automated programs such as Memon's are unusual and a major step forward. "Most applications simply don't handle images that have been torn into pieces and scrambled that well," Richard says. "His technique takes those shreds and puts them back together." When a media card inside a camera starts to fill up, new photos are often stored in separate pieces wherever space is available. When the information detailing where these file fragments are stored is erased, recovering those slivers is difficult. Memon's software also could be used by law enforcement to recover deliberately deleted files. Marcus K. Rogers, head of Purdue University's Cyber Forensics Program, says his lab often is asked to recover deleted images from hard drives. "Quite often that's just where the smoking guns are found," he says.
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The only thing I can say is, "Dr. Memon, where were you when I needed you?"

I Have a software called "URGENTRECOVERY-PRO" twas so amazing software, if you deleted the picture accidentally, there's no worry!!! even the recent files from the "FORMATED" card. you can still retrieved it!!!

i just use pc inspector to recover accidentally deleted files.. or delete for now and recover later ^_^

best thing about pc inspector is that its a freeware