I am a big fan of Sokoban. Among the many implementations I have seen, I still enjoy playing the version for the Palm written by Electron Hut the most. Unfortunately, support for this program has been discontinued as of 2010. This also means that the level converter, which used to be located at http://www.electronhut.com/games/sokoban/converter/, is no longer available. Since the game uses a proprietary format for storing the levels, I was not able to convert any new levels for my Palm.
For this reason, I reverse engineered the format and hacked together a small C++ program to convert levels from the Sokoban text format (also known as XSB, cf. this minimal description) to a PDB file for the Palm usable with the Electron Hut game.
Note that the code is rather ugly, has no documentation, and does only minimal error checking. However, it Works For Me, and I hope it may be helpful. Compiling it should be a snap, as it consists only of a single source and a header file, and uses only basic C++ functions:
If you have any trouble with compilation, or if you add any improvements, please let me know.
I place the code into the public domain.