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Aside from a forensics team/data recovery company ($$$$) getting hold of your computer, I'm pretty sure it's beyond the abilities of the average user. I hope you didn't lose anything important!
 
I've spoken to a few people that have had decent results in recovering files with Data Rescue II. It costs $100, and the free version can rescue files that are up to 500kb in size. If ya need it bad enough, you could justify paying for it.. if not, *shrugs :p
 
I've once recovered quite a bit of deleted data using File Salvage, it wasn't perfect though and alot of files, especially big ones, were pretty much permanently damaged. Small jpegs usually turned out fine though.
 
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