A command line editor/parser for the NBT player data file format used by Minecraft. Fully scriptable, i use it to periodically set the player's XP to zero to prevent 1.8 orb lag.
Examples can be found in the two shell scripts mcplayerget and mcplayerset.
It uses TheFrozenFire's NBT Decoder/Encoder library. Clone this tree with the "--recursive" option to have it pulled as well. Requires the GMP Extension for PHP.