Thanks to everyone for their input, especially Zaniax.
FileShredPPC 2.0 is sporting a new option, in addition to the file shred options it had before: Wipe Free Space. It now wipes free space on a user-selected volume using the same overwrite options set for file shredding. Again, you can set it from 3 to 10 overwrites.
Please note that wiping free space on a volume takes
substantially longer than wiping a file. YMMV. And when it's generating random bytes it tends to slow down a bit.
it does support storage and cf cards with names other than the defaults. the volume loader filters out the common directory names like "\windows" and "\my documents" so you should get your sd/cf card in the list, no matter what name it has.
You can get it at
http://pocketpcapps.net/fileshredppc.aspx
Please make sure you uninstall version 1 before installing the new version!
It's free, of course, but donations are always appreciated ;)
comments and suggestions welcome. Enjoy!! :)