Alright, I was playing a 360, and all of the sudden I got an E68 error. Looked it up, turns out it's a hard drive error.
Since it's no longer under warranty, I took the sucker out and popped it into my external enclosure. I did two operations to try to get all of the data off.

and

and both eventually stopped with an I/O error.
As far as I know, both commands will just pull data from the drive and put it into files.
Since XBOX 360 uses a FAT32 filesystem, I selected Intel in testdisk. I got the missing endmark 0xAA55 error, and continued to scan the drive for any hope of recovery. After it hits cylinder 16188/19219 it farts out for a second, then continues on. (It used to give me loads of I/O errors until I Ctrl+C'd it at that point, but for some reason it's kinda stopping right there, then continuing. This happened after I knocked the power out of the enclosure accidentally, so I don't know if it's good or bad)
After test disk did it's first scan, I requested as deeper search, which still turned up nothing.
I'm drawing a blank right now, so I've decided to turn to this forum. Any help would be greatly appreciated.

Well I was definitely wrong in thinking that the drive had FAT32. I think I've got the problem figured out now, I need a new drive.