I'd like to see a field to record the original filename when uploading, especially for challenge entries. This would make it easier to find when asked for validation, and would replace my current system of writing the original filename on a yellow sticky. :)
The name of the file you upload appears in the Title field. I copy and paste it into the Additional Info area before assigning "real" title. Like others have mentioned, I make the original image number part of the final name as well.
When I do save for web on potential submissions I also keep the original file name attached to the shot. For example: Candid-CRW_3527.jpg These all go into a submissions folder. Then when I need to find the original it is much easier...