Sokoban++ - A free Sokoban player with 50 built in levels.
Fish Fillets - Next Generation - Fish Fillets NG is strictly a puzzle game. It is a Linux port of the wonderful puzzle game Fish Fillets from ALTAR interactive.
YSokoban - A classic but still maintained Sokoban player
JSoko - JSoko is a Java program for playing the Sokoban game. It features path finding, auto push, auto solving, undo/redo, deadlock detection, and more.
Simple Sokoban - Simple Sokoban is a (simple) Sokoban game aimed at playability and portability across systems.
Sokoban 3D - It's Classic Sokoban, but in 3D!