Bukkit

The current config file is settings.prop

Default configuration:
#
#Sat May 24 15:59:27 EDT 2014
npcDieAfterTime=false
tagMessageDamaged=You have been hit by [player]. Type /ct to check your remaining tag time.
blockEditWhileTagged=true
blockCreativeTagging=true
dontSpawnInWG=false
Enable-Debugging=false
onlyDamagerTagged=false
Version=6.1.4
commandMessageTagged=You are in combat for [time] seconds.
npcDespawnTime=-1
commandMessageNotTagged=You are not currently in combat.
disabledCommands=[]
InstaKill=false
npcName=PvpLogger
sendMessageWhenTagged=false
blockTeleport=false
Tag-Duration=10
disabledWorlds=[exampleWorld,exampleWorld2]
mobTag=false
blockEnderPearl=false
tagMessageDamager=You have hit [player]. Type /ct to check your remaining tag time.
blockFlying=false
playerTag=true
DropTagOnKick=true

What each one does:

npcName: This is the name of the NPC that you want to spawn. If you input "number", it will replace "number" with the NPC's number. If you put "player", it will replace "player" with the player's name. You can also put something like "playernumberxx". If I were to pvp log the NPC would be named something like "cheddar2621xx". If you don't put "player" or "number", the plugin will automatically append a number to the end of the name.
Beware: Putting the NPC name as just "player" will cause an incompatibility with Heroes, but it will allow their skins to show.

disabledWorlds: Worlds which will not spawn NPCs

Tag-Duration: Amount of seconds for a combat tag to last

disabledCommands: Commands which are disabled while in combat. Example: [/warp,/home,/spawn]. If you put [all] in this field, all commands will be blocked. Example: disabledCommands=[all]

Enable-Debugging: Debug mode on/off

Version: Version of the plugin. DO NOT TOUCH THIS!

InstaKill: Whether a person automatically dies when they PvP log (true) or if it'll spawn an NPC (false)

npcDespawnTime: The time it takes for and Npc to despawn in seconds after the person pvp logs. "-1" for the npcs not to despawn.

blockEditWhileTagged: Whether people can edit blocks while tagged or not.

npcDieAfterTime: If the npc (when it despawns due to npcDespawnTime) dies and drops their stuff (true) or the npc despawns and the person keeps their stuff (false)

dontSpawnInWG: If set to true, NPCs will not spawn in a worldguard region that has invincibility or no pvp

commandMessageTagged: Allows server owners to set the custom message for the /ct command. [time] is replaced with the time left for the tag.

commandMessageNotTagged: Allows server owners to set the custom message for the /ct command when a player is not tagged.

sendMessageWhenTagged: When set to true, sends tagMessageDamaged to both players when they become tagged.

blockTeleport: When set to true, blocks teleports caused by plugins (BEWARE, THIS ALSO MAKES IT SO OTHERS CAN'T TP THE PERSON AWAY EITHER)

tagMessageDamager: Sent to attacker. [player] is replaced with the player they hit.

tagMessageDamaged: Allows server owners to set custom tag messages. Sent to attacked person. [player] is replaced by player who hit them.

DropTagOnKick: When set to true, will cause players to stop being tagged when they get kicked from the server.

blockEnderPearl: Blocks ender pearl usage while in combat

onlyDamagerTagged: Set if only the damager in a pvp battle is tagged.

mobTag: Set if a player will be tagged by mobs

playerTag: Set if a player will be tagged by other players

blockCreativeTagging: Block the ability for tagging anyone for people in creative mode

blockFlying: When true, will block flight when a player is tagged