I was wandering through portablefreeware.com, and I stumbled accross a couple of open source file recovery tools that look interesting.
One of them is the discription from the FileExtractor home page:
FileExtractor is a free (open source) tool for recovering files from a binary data source. Sources such as digital cameras, partitions, harddrives, memory sticks or floppy disks may be corrupted, deleted or formatted by mistake. Once the file system is destroyed you need a tool such as FileExtractor to recover your files.
The website is http://kkfileextractor.sourceforge.net/
The other one I found was PhotoRec. Here's the discription from their home page:
PhotoRecis file data recovery software designed to recover lost files including video, documents and archives from Hard Disks and CDRom and lost pictures (thus, its 'Photo Recovery' name) from digital camera memory. PhotoRec ignores the filesystem and goes after the underlying data, so it will still work even if your media's filesystem has been severely damaged or re-formatted.
the web page is http://www.cgsecurity.org/wiki/PhotoRec
I haven't tried them out yet, but either one of them would make a useful app.