I think your idea about a command for beast kills is very good.
*Perhaps even a second command for how many beasts you have killed, and of what type? "Highscore/Beasts/Ecliptic Hell Angel's #1. Anthas"*
This would help alot of players because it does become hard especialy for those with more then 1 account to remember exactly what they have and havent killed. Of course there is always the old Notepad altative