This plugin allows you to put whitelists on worlds. It stores the worlds in the config.yml and it is possible to do it manually but I recommend using the commands!
Commands:
/wwhitelist add/remove player world - Removes or adds a player to a world's whitelist!
/wwhitelist on/off world - Toggles a world's whitelist!
/wwhitelist help - Shows command information
Permissions:
/wwhitelist add - wwhitelist.add
/wwhitelist remove - wwhitelist.remove
/wwhitelist on - wwhitelist.on
/wwhitelist off - wwhitelist.off
wwhitelist.bypass - Allows users/groups to bypass the whitelist for all worlds!
wwhitelist.WORLD Allows a users/groups to bypass a world's whitelist.