In the arenas downvoting seems rampant. Most notice that downvoting occurs within the first day or so. Here is an idea that I've come up with to battle against this.
Monday- Only 5 stars allowed (Making it so that only 5 stars could be selected)
Tuesday- 5 and 4 stars allowed
Wednesday- 5,4 and 3 stars allowed
Thursday- 5,4,3 and 2 stars allowed
Friday- 5,4,3,2 and 1 star votes allowed (which gives the haters two days to hate all they want without damaging the avg's too much)
I really think this is fair. If people want to 1 star on a Monday they can wait until friday to 1 star the entry they hate. Also when people 1 star vote an entry they should be forced to provide a comment as to why they rated 1 star (maybe even a list of the namesand what they voted could be listed). That way intimidation will prevent 1 star ratings that have no reason. If the person that rates a 1 on the entry does not have a viable reason as to why they voted a 1 star then it can be reported for mods or admins to decide to void that vote.