Bukkit

These commands are for PRE 1.0 versions
/xp – Shows the player how much experience they have and their experience level.
/zeroall – Resets the players experience orbs and experience level to zero.
/zeroxp – Resets the players experience orbs to zero only.
/zerolevel – Resets the players experience level to zero.
/setlevel - Allows a player, with the permission, to set the experience level of a player

1.0 commands
/exp - Shows the help page
/exp check (player) - Shows the player what their experience orbs and level is.
/exp zeroall (player) - Resets the players experience orbs and level to zero.
/exp zeroxp (player - Resets the players experience orbs to zero only.
/exp zerolevel (player) - Resets the players experience level to zero
/exp setlevel (player) <level> - Allows a player, with permission, to set the experience level of a player

NOTE: (player) is NOT required. (player) will only be used if the sender as correct permission node.