If I haven't got any backups, is there any way of recovering, or partially recovering the world from a corrupted save file?
- copy & rename the server world folder into your solo save folder:
C:\documents and settings\USERNAME\application data\.Minecraft\saves
- Start & quit a new solo game
- Copy the .dat files from the new solo game into the corrupted world
- Start the corrupted world in solo mode to check
copy the repaired world back to the server folder & rename
If that doesn't work, try deleting the \players folder in that world as a last resort (player data will be lost)
This wasn't the fix for me, but there's also a Chunkster utility that will verify the world's region chunk files for corruption individually, if the problem happens to be in one of those.
A useful tool that I've run into out there is something called Minecraft Region Fixer that may be able to help you solve your issue.
Minecraft Region Fixer is a command line-based tool that scans the files of a Minecraft world save and checks the file structures to see if there are corrupted chunks, or if there are other issues with the world save as well.
If you are not familiar with using a command line, it will be pretty easy if you read the author's documentation on his post. He does a good job of being clear and thorough, and hopefully you will be able to use it to solve your problem!