Allow !highlight to be set as a user group (mod level 1, for instance)/individual command (give command rights to someone else, say an editor you don't task with chat moderation)
Have !highlight auto-output the !uptime command equivalent into the log file.
Add an to option place the log file somewhere specific (e.g. a dropbox folder so that your editors can view it). (Email capability/twitch whisper/google docs functionality would be awesome as well).