A plugin with a config file that has actions that should happen when a player joins, leaves, dies, etc would be really useful. The file would look something like this for the "death" area: --- When a player dies; name, score, causeOfDeath{ ban #name; say #name has died of #causeOfDeath with a score of #score; //text in red is entered by the user. } --- You just enter the commands using the provided variables for the event for when a player does something. It would also be nice if it could partner with NoCheat, which already has something like this, to make one config file for both. NoCheat can also execute commands with variables when a player does a certain action like flying, running, or some other cheat.
I needed a command on login plugin a few days back and a very nice gentleman helped me out. http://dev.bukkit.org/server-mods/commandonstart/ You can set it to do any command on login. It's only log in not out