Hmm, trying your hand at producing some por... uh... nevermind.
Anyway, undelete software especially for memory cards does exist;
PhotoRescue is one example. Memory cards use the FAT or FAT32 filesystems, and the same principles of file storage apply to them as apply to floppies and hard disks: unless more files have been written to the storage device on top of the location where the original data was, the data is still there, and there's a good chance that some good undelete software can recover the entry in the directory listing.